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- 2. WHAT IS THE WORLD MADE OF?
- 3. elements
- 5. Democritus 370 a. C . From the Greek ἄτομον («átomon»): α (a), that means “with out, not“ τομον (tomon), that means “cutting“ ¨Indivisible particle¨ How can it be divided infinitely?
- 6. The atom according to Democritus: Solid Simple Homogeneous Without form Eternal Invisible
- 7. The philosopher´s stone Is a mythic substance capable of turning base metals such as mercury into gold. It is also called the elixir of life, useful for rejuvenation and for achieving immortality.
- 8. Alchemy Protoscientific tradition that attempted the transmutation of "base metals" (e.g., lead) into "noble metals" (particularly gold); the creation of an elixir of immortality; and the creation of panaceas able to cure any disease. From the Greek χημεία (khemeia) that means ¨casting¨
- 10. Chemistry comes from the Greek word χημεία (khemeia) that means «pour together», carrying the notion of the ancient alchemy pursuit of transmutation of base metals into gold.
- 12. THE ATOM
- 13. SUBATOMIC PARTICLES PROT0N NEUTRON ELECTRON ATOM: The smallest unit of matter which still retains its identity as a chemical element. Protons: Positively charged. Neutrons: It has no charge Electrons: negatively [+] [+/-] [-] *Protons and neutrons, collectively called nucleons
- 14. atomic number PROT0N NEUTRON ELECTRON The number of protons in an atom is referred to as the atomic number (represented by the symbol Z). Is used to distinguish one element from another. [+] Protons
- 15. Atomic mass number PROT0N NEUTRON ELECTRON The sum of the number of protons and the number of neutrons in an atom determine an element’s mass number (represented by the symbol A). [+] [+/-] + Protons Neutrons
- 24. KEY TAKEAWAYS FROM PREVIOUS LESSON • An atom is composed of two regions: the nucleus, which is in the center of the atom and contains protons and neutrons, and the outer region of the atom, which holds its electrons in orbit around the nucleus. • The number of protons determines an element’s atomic number and is used to distinguish one element from another. • The outermost regions of the atom are called electron shells and contain the electrons (negatively charged). • Each electron has a negative charge (-1) equal to the positive charge of a proton (+1).
- 25. Bohr’s Model of the Atom The number and type of orbitals increases with increasing atomic number. Neutral atoms of each element contain an equal number of protons and electrons. TO HAVE IN MIND
- 26. Bohr’s Model of the Atom The number and type of orbitals increases with increasing atomic number. Neutral atoms of each element contain an equal number of protons and electrons. TO HAVE IN MIND
- 27. Bohr’s Model of the Atom Atoms are most stable if they have a filled valence shell of electrons. These electrons are responsible for interaction between atoms and the formation of chemical bonds. TO HAVE IN MIND Electrons in the outer shells
- 28. For the first principal energy level, having two electrons in it is the most stable arrangement, while for all other levels outside of the first, eight electrons are necessary to achieve the most stable state. Bohr’s Model of the Atom TO HAVE IN MIND
- 29. The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons. In order to write the Lewis symbol for an atom, you must first determine the number of valence electrons for that LEWIS SYMBOL TO HAVE IN MIND In the Lewis symbol for an atom, the chemical symbol of the element (as found on the periodic table) is written, and the valence electrons are represented as dots surrounding it. Hydrogen Oxygen Water
- 30. KEY TAKEAWAYS FROM TODAY´S LESSON • Neutral atoms of each element contain an equal number of protons and electrons. • The outermost regions of the atom are called electron shells and contain the electrons (negatively charged). • The number and type of orbitals increases with increasing atomic number. • Electrons closest to the nucleus will have the lowest energy. Electrons further away from the nucleus will have higher energy. • Electrons fill orbitals starting at the lowest available energy state before filling higher states.
- 31. HANDS TO WORK! • Complete the chart. Based on the ID, find the missing information. ID Z N e- A Valence e- Lewis dots Berylium Carbon Oxygen Sodium Sulfur Chlorine Calcium Xenon
- 32. KEY TAKEAWAYS FROM LAST LESSON • Valence level: The outermost principal energy level, which is the level furthest away from the nucleus that still contains electrons. • Valence electrons: electrons contained in the valence level. These electrons are the farthest away from the nucleus and, therefore, are the ones most loosely held by its attractive force and participate in the formation of chemical bonds. . • Octate rule: Atoms gain, lose, or share electrons in their valence level in order to achieve greater stability. Eight electrons are necessary to achieve the most stable state (page 129). • Lewis symbols: represent the valence electrons as dots surrounding the elemental symbol for the atom (pages 109-110).
- 33. THE PERIODIC TABLE Group: A column in the periodic table that consists of elements with similar chemical reactivity, because they have the same number of valence electrons. Periods: The elements are arranged in seven horizontal rows, called periods or series 1 2 3 4 5 6 7 Read pages 115-
- 37. Naming Groups of Elements Give the group name for the following elements and write them down into your notebook: (a) chlorine (b) calcium (c) sodium (d) sulfur (e) krypton (f) selenium (g) barium (h) lithium
- 39. KEY TAKEAWAYS FROM LAST LESSONS • Neutral atom: if an atom contains as many electrons as protons, the negative and positive charges balance and the atom is electrically neutral. All the elements of the periodic table are neutral but that doesn´t mean they can´t become positive o negative. Atoms are more likely to lose or gain electrons rather than loosing or gaining protons. • Ions: when an atom have different number of electrons than protons, such an atom or molecule is called an ion. • Atoms that loose one or more electrons become a positive ion (cation). • Atoms that gain one or more electrons become a negative ion (anion).
- 41. CHEMICAL BONDING
- 42. CHEMICAL BONDING A chemical bond is a lasting attraction between atoms or ions that enables the formation of compounds. The bond may result from: 1. the electrostatic force between oppositely charged ions as in ionic bonds. 2. through the sharing of electrons as in covalent bonds. Read pages 129-
- 43. Complete outer shells (both ions satisfy the octate rule). Attraction of opposite charges ends up in formation of an ionic bond Ionic Bond Read page 130
- 46. NATURE OF MATTER 1. Anything that occupies space and has mass. 2. 95% of the universe is empty space, the other 5% is matter (galaxies, stars, planets, rocks, water, etc.) 3. Matter is neither created nor destroyed, it is only transformed (Lavoisier law).
- 47. PURE SUBSTANCES MIXTURES ELEMENTS (substances composed of a single type of element) COMPOUNDS (substances made up of two or more elements joined) HOMOGENEOUS COLLOIDAL HETEROGENEOUS A substance is a form of matter with unique properties that make it different from every other substance. A substance consisting of two or more pure substances that are physically mixed but not chemically combined. Mixtures can be separated into simpler substances by physical means It´s components can not be seen by the naked eye (Air, water, bronze; copper and tin) It´s components can be seen only by optical instruments like the microscope (milk, mayonnaise, blood) It´s components are incompleteley mixed, so the components can be seen with the eye alone (oil and water, granite)
- 51. SOLID PARTICLES These particles exists in 4 different forms or states STATESOF MATTER Sublimation LIQUID Melting Solidification Evaporation Condensation Fixed volume Fixed shape Fixed volume Assumes the shape of the container Assumes the volume of the container Assumes the shape of the container PLASMA Ionization Deionization has has More attraction than repulsion Attraction equal to repulsion Less attraction tan repulsion A hot gas in wich atoms are partially broken down to form charged particles, or ions. Matter change from one state to another by the efect of temperature and pressure, either increasing or decreasing caloric energy. Progresive changes of state: They occur when we increase the temperature of their bodies through the application of heat, such as: melting, evaporation, sublimation and ionization. Regressive state changes: They are those which occur when the temperature of the bodies decreases, that is, they are colder, such as: solidification, condensation, deposition and deionization. MATTER Composed by Deposition GAS
- 52. READING CHEMICAL FORMULAS 2H2O (l) Physical state of matter: • l: liquid • g: gaseous • s: solid • ac: aqueous Chemical compound The big number in front of a compound represents the amount of molecules The small number after an element represents the amount of atoms of an element within a molecule It´s a written representation of a chemical compund. The elements in a compound are represented by their chemical symbols, and the ratio of different elements is represented by subscripts.
- 53. The Table below shows four examples of compounds and their chemical formulas. The first two compounds are ionic compounds, and the second two are covalent compounds. Each formula shows the ratio of ions or atoms that make up the compound. If a charge is present, it’s indicated in superscript, with a sign (+/-) and a number if more than one charge is present. For example, calcium ions have two positive charges so are written Ca2+.
- 54. MOLAR MASS
- 55. H= 2 X 1 amu = 2 amu O= 1 X 16 amu = 16 amu 18 g/mol 2
- 56. STOICHIOMETRY: CHEMICAL REACTIONS Chemical reaction: when atoms or molecules collide or interact producing different substances. Reactants: The symbols of the substances that react. Usually, they are written on the left. Products: The symbols of the substances produced in the reactions. Usually, they are written on the right of the equation.
- 57. Law of conservation of mass: ¨Atoms (matter) are not created or destroyed in chemical reactions, only JOHN DALTON LAW OF CONSERVATION OF MASS
- 59. The Algebraic Balancing Method This method of balancing chemical equations involves assigning algebraic variables as stoichiometric coefficients to each species in the unbalanced chemical equation. These variables are used in mathematical equations and are solved to obtain the values of each stoichiometric coefficient. C6H12O6 + O2 → CO2 + H2O aC6H12O6 + bO2 → cCO2 + dH2 O C6H12O6 + 6O2 → 6CO2 + 6H O
- 62. ¿Qué es un enlace químico? Es el conjunto de fuerzas que mantiene unidos a los átomos, iones y moléculas cuando forman distintas agrupaciones estables. H Cl Cl H Ácido clorhídrico ENLACE
- 63. Fórmula molecular Elementos presentes Número de valencia Modelo atómico Estructura de Lewis del compuesto Cálculo del número de oxidación Tipo de enlace FeO Fe O 2 6 Fe O Fe O +2 -2 FeO
- 66. If U-235 is bombarded with a neutron (light blue small circe), the resulting U-236 produced is unstable and undergoes fission. The resulting elements (shown here as Kr-92 and Ba-141) do not contain as many nucleons as U- 236, with the remaining three neutrons being released as high-energy particles, able to bombard another U-235 atom and maintain a chain reaction.
Editor's Notes
- People, from ancient times have asked WHAT IS THE WORLD MADE OF? AND WHAT HOLDS IT TOGETHER? What are the fundamental building blocks of nature. The Word ¨fundamental¨ is key here. By fundamental building blocks we mean objects that are not made of anything smaller.
- People sought to organize the world around them into fundamental elements, such as earth, fire, wind and water
- Quintessence means "pure, fresh air" or "clear sky“, it was thought to be the pure essence that the gods breathed, filling the space where they lived, analogous to the air breathed by mortals.
- UNCUTTABLE What would happen if you just kept slicing something in halt forever? You would end up with one, pure, unbreakable bit of that substance. Democritus call this unbreakable particle ¨atom¨. Of course, we know from the world war II, atoms can be broken as well. An ancient term of philosophical speculation (in Leucippus, Democritus); revived scientifically 1805 by British chemist John Dalton.
- The most commonly mentioned properties are the ability to transmute base metals into gold or silver, and the ability to heal all forms of illness and prolong the life of any person who consumes a small part of the philosopher's stone diluted in wine.
- transmutation: The transformation of one element into another by a nuclear reaction. alchemy: The ancient search for a universal panacea, and for the philosopher’s stone. The process eventually developed into chemistry.
- the Father of Modern Chemistry he practiced alchemy until the end of his life, believed that he had witnessed transmutation the work is an acknowledged landmark of science the terms chemistry and alchemy (which derive from the same word) were basically synonymous. alchemy was redefined as gold making and driven out of respectable laboratory practice. The term chemistry remained, symbolically purified of its charlatanry. In the 18th century, Antoine Lavoisier replaced the alchemical theory of elements with the modern theory of chemical elements
- pouring molten metal
- pouring molten metal
- An atom is composed of two regions: the nucleus, which is in the center of the atom and contains protons (positively charged) and neutrons (no charge), and the outermost regions of the atom are called electron shells which holds (contain) its electrons (negatively charged) in orbit around the nucleus. Atoms consist of three basic particles: protons, electrons, and neutrons. To hold positively charged protons together in the very small volume of a nucleus requires very strong attractive forces because the positively charged protons repel one another strongly at such short distances. The force of attraction that holds the nucleus together is the strong nuclear force. (The strong force is one of the four fundamental forces that are known to exist. The others are the electromagnetic force, the gravitational force, and the nuclear weak force.) This force acts between protons, between neutrons, and between protons and neutrons.
- Atoms have different properties based on the arrangement and number of their basic particles. It weighs 1 amu (atomic mass unit). Protons and neutrons both weigh about one atomic mass unit (amu). distinguishes one element from another. For example, carbon’s atomic number (Z) is 6 because it has 6 protons.
- When considering atomic mass, it is customary to ignore the mass of any electrons and calculate the atom’s mass based on the number of protons and neutrons alone. Neutral atoms of each element contain an equal number of protons and electrons. The number of neutrons can vary to produce isotopes, which are atoms of the same element that have different numbers of neutrons. The number of electrons can also be different in atoms of the same element, thus producing ions (charged atoms). Given an atomic number (Z) and mass number (A), you can find the number of protons, neutrons, and electrons in a neutral atom. For example, a lithium atom (Z=3, A=7 amu) contains three protons (found from Z), three electrons (as the number of protons is equal to the number of electrons in an atom), and four neutrons (7 – 3 = 4). calculate how many neutrons an element has by simply subtracting the number of protons from the mass number. Protons and neutrons both weigh about one atomic mass unit (amu).
- atomic mass unit (amu) or one Dalton.
- The Bohr model of the atom does not accurately reflect how electrons are spatially distributed around the nucleus as they do not circle the nucleus like the earth orbits the sun. Its not perfectly accurate but for what we need right now its gonna do just fine The closest orbital to the nucleus, called the 1s orbital, can hold up to two electrons. The 1s orbital is always filled before any other orbital. On the periodic table, hydrogen and helium are the only two elements in the first row (period); this is because they are the sole elements to have electrons only in their first shell, the 1s orbital. After the 1s orbital is filled, the second electron shell is filled The second electron shell may contain eight electrons. This shell contains another Lithium (Li) contains three electrons that occupy the first and second shells. Two electrons fill the 1s orbital, and the third electron then fills the 2s orbital.
- The electrons of an atom are typically divided into two categories: valence and core electrons. Valence electrons occupy the outermost shell or highest energy level of an atom while core electrons are those occupying the innermost shell or lowest energy levels. the number of valence electrons is equal to the atom’s main group number. Valence electrons determine the reactivity of an atom. Atoms gain, lose, or share electrons in their valence level in order to achieve greater stability, or a lower energy state. For the first principal energy level, having two electrons in it is the most stable arrangement, while for all other levels outside of the first, eight electrons are necessary to achieve the most stable state.
- The noble gases represent elements of such stability that they are not chemically reactive, so they can be called inert. In other words, they don’t need to bond with any other elements in order to attain a lower energy configuration. We explain this phenomenon by attributing their stability to having a ‘full’ valence level.
- elements in the periodic table react to form bonds in which valence electrons are exchanged or shared in order to achieve a valence level which is filled, just like in the noble gases. We refer to this chemical tendency of atoms as ‘the octet rule,’ and it guides us in predicting how atoms combine to form molecules and compounds. The Lewis symbol for an atom depicts its valence electrons as dots around the symbol for the element.
- Lewis symbols do not visualize the electrons in the inner principal energy levels. https://uen.pressbooks.pub/introductorychemistry/chapter/lewis-dot-symbols-and-lewis-structures-writing-lewis-symbols-for-atoms/
- Many elements differ dramatically in their chemical and physical properties, but some elements are similar in their behaviors. periodic law, is as follows: the properties of the elements are periodic functions of their atomic numbers. A modern periodic table arranges the elements in increasing order of their atomic numbers and groups atoms with similar properties in the same vertical column. Each box represents an element and contains its atomic number, symbol, average atomic mass, and (sometimes) name. The elements are arranged in seven horizontal rows, called periods or series, and 18 vertical columns, called groups. For the table to fit on a single page, parts of two of the rows, a total of 14 columns, are usually written below the main body of the table.
- For the table to fit on a single page, parts of two of the rows, a total of 14 columns, are usually written below the main body of the table.
- https://www.texasgateway.org/resource/lewis-valence-electron-dot-structures
- For the table to fit on a single page, parts of two of the rows, a total of 14 columns, are usually written below the main body of the table. We can sort the elements into large classes with common properties: metals (elements that are shiny, malleable, good conductors of heat and electricity—shaded yellow); nonmetals (elements that appear dull and are poor conductors of heat and electricity—shaded green); and metalloids (elements that conduct heat and electricity moderately well and possess some properties of metals and some properties of nonmetals—shaded purple). The elements can also be classified into the main-group elements (or representative elements) in the columns labeled 1, 2, and 13–18; the transition metals in the columns labeled 3–12; 1 and inner transition metals in the two rows at the bottom of the table (the top-row elements are called lanthanides and the bottom-row elements are actinides). alkaline earth metals, with similar properties among members of that group. Other groups with specific names are the pnictogens (group 15), chalcogens (group 16), halogens (group 17), and the noble gasses (group 18, also known as inert gasses).
- Solution The family names are as follows: (a) halogen (b) alkaline earth metal (c) alkali metal (d) chalcogen (a) noble gas (b) Chalcogen (c) alkaline earth metal (d) alkali metal
- A chemical bond is a lasting attraction between atoms or ions that enables the formation of compounds. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing of electrons as in covalent bonds.
- The chemical bond can change the physical state of matter and the properties of the original components.
- Ionic bonds ara characterized by a transfer of electrons. Since transferring electrons between atoms forms ions of opposite charge, there will be a forcé of attraction- a chemical bond- between the ions. A chemical bond in wich positivley charged ions are electrically attracted to negatively charged ions is an ionic bond. Chlorine (Cl) has 7 electrons, it must gain one electron to satisfy the octate rule. The compound formed from its ionic bond is sodium chloride (NaCl), or common table salt. In a ionic bond we have an non-metal atom and a metal atom.
- A chemical bond that results from the sharing of valence electrons between non-metal atoms is a covalent bond. In such compounds, the electrons are shared by the overlapping of the valence electron clouds of two atoms.
- About 118 elements have been identified thus far; 88 occur naturally, while the rest have been produce artificially in the lab.
- Tabla 2.7 página 21 Section review 2.1 página 23
- Melting: It is the change from the solid state to the liquid state through the application of heat. The temperature at which this process occurs depends on each substance, being called at said temperature “Fusion Point”. In the case of gold, for example, it is 1064º C while in the case of ice it is 0º C. Solidification: It is the passage of a substance from the liquid state to the solid state. For this process to occur, the substance must reach a certain temperature known as the “Freezing Point” and, because of this process is the reverse of the melting point, Evaporation: The temperature necessary to reach this point is called the “Boiling Point”. For the case of silver it is 2162 ºC, while in the case of water it is only 100 ºC. Condensation: It is the change of gaseous state to liquid state due to a decrease in the temperature. The temperature at which this transformation occurs is known as the “Condensation Point” and corresponds to the Boiling Point because of this process is inverse to that of evaporation. Some of the most common natural forms of plasma include the Northern Lights (also called aurora) and lightning. Direct Sublimation: dry ice (CO2) in the laboratory, we can see that the transformation is immediate when we add a few drops of ethanol. Regresive Sublimation: t is the change from the gaseous state to solid state but without passing through the liquid state. Nieve. Las bajas temperaturas provocan que el vapor de agua de las nubes se convierta en nieve.
- a formula that lists all the atoms in that molecule. Each element is represented by its atomic symbol in the Periodic Table – e.g. H for hydrogen, Ca for calcium. If more than one atom of a particular element is present, then it’s indicated by a number in subscript after the atomic symbol — for example, H2O means there are 2 atoms of hydrogen and one of oxygen. The subscript 2 after the H shows that there are two atoms of hydrogen in the molecule. The O for oxygen has no subscript. When there is just one atom of an element in a molecule, no subscript is used in the chemical formula.
- Connect the atomic masses (atomic weights) of all atoms within the molecule to calculate the molar mass (in amu). Find the atomic mass for each element using the mass shown in the Periodic Table. Multiply the subscript (number of atoms) times that element’s atomic mass and add the masses of all the elements in the molecule to obtain the molecular mass. Molar mass is typically expressed in grams per moles (g/mol)
- The sum of the masses of the products is always equal to the sum of the masses of the ractants.
- At first glance these chemical reactions might seem like a mess of information, but there are patterns among them. It’s helpful for chemists to sort all the chemical reactions into categories so that they can make predictions about how chemicals might react. There are five main types of chemical reactions: combination which is also known as synthesis, single replacement, double replacement, decomposition and combustion. Now, not every reaction falls perfectly into one category, sometimes a reaction falls under two categories. But there are some key features to each category. Let’s start with combination reactions. Combination reactions Combination reactions combine the two or more substances to form a new single substance. This example is elemental magnesium and oxygen combining to form magnesium oxide. The two elements combined and formed one ionic compound. Even though it made two units of magnesium oxide, they are the same substance. So here we have the balanced chemical equation, a particulate drawing of that same reaction and now here’s a general equation for combination reactions. A + B yields substance AB. The reverse version of this kind of reaction is called decomposition. Decomposition reactions. In this reaction, things fall apart instead of coming together. A single substance breaks down into two or more simpler products. Here is an example of hydrogen peroxide breaking down into water and oxygen. Usually, decomposition reactions need heat, or fire or electricity to get started. This reaction can happen quickly with a catalyst like yeast or manganese dioxide. So we have the equation, a drawing and now a simple formula for decomposition, AB yields A plus B. The resulting compounds are smaller and simpler than the starting compound. Let’s look at the next type of reaction Single Replacement. Single replacement reactions. In this reaction, one element replaces a second element in a compound. We’ll use the example of zinc reacting with iron chloride to make zinc chloride and elemental iron. The two metals in this case, have swapped places. So here we have an equation, drawing and now a simple formula for single replacement reactions, A plus BC yields AC + B. But not all single replacement scenarios actually work. In order to see if the swap will occur, we need to reference a chart the activity series of metals. The more active metals are toward the top and the metals decrease in their activity as you move to the bottom. In the previous reaction, zinc was the individual element and was higher than iron on the activity series. So this reaction occurred. But if we tried to react elemental iron with zinc chloride, nothing would happen, because iron has a lower activity than zinc. Now let’s look at the next type of reaction Double Replacement. Double replacement reactions. This reaction is similar to single replacement except we’re starting with two compounds. The reaction has an exchange of positive ions between the two compounds. In This example copper(II) chloride and hydrosulfuric acid swap their positive ions to make copper sulfide and hydrochloric acid. So here we have an equation, drawing and now a simple formula for double replacement reactions, AB plus CD yields AD + CB. You can see from this equation that A and C have switched places and those represent the positive ions. Usually a double replacement reaction creates one of three products a precipitate, molecular substance or a gas. In this double replacement reaction, we started with two aqueous solutions and end with aqueous hydrochloric acid but solid copper sulfate. This will sink, or precipitate to the bottom of the container. Another possible product would be a molecule. In this example, we start with aqueous substances, but one of the products is a liquid, the water and the other product is still aqueous. Lastly, another possible product from a double replacement reaction is a gas. Again, we start with aqueous substances, sodium cyanide and sulfuric acid, but form a gas as a product: poisonous hydrogen cyanide gas. Don’t try this one at home, folks. Combustion The last type of chemical reaction is a fun one, combustion. In combustion an element or compound, typically a hydrocarbon, reacts with oxygen, often producing heat or light. So here is the combustion of a hydrocarbon, called methane. The combustion with a hydrocarbon will always make water and carbon dioxide as products. This makes predicting the products really easy in this case! So here we have an equation, drawing and now a formula for the combustion of a hydrocarbon. The x and y variables here provide a shortcut for balancing the equation as well. But not all combustion reactions happen with hydrocarbons. The combustion of magnesium in oxygen is both a combustion reaction AND a combination reaction. Remember, there are some reactions that can fit more than one type of reaction.Thanks 5:28 for watching this episode of Teacher’s Pet, don’t forget to like and subscribe and follow 5:31 me on twitter @SciencePet
- In this example, the reactants are glucose (C6H12O6) and oxygen (O2) and the products are carbon dioxide (CO2) and water (H2O) Step 2 Now, algebraic variables are assigned to each species (as stoichiometric coefficients) in the unbalanced chemical equation. In this example, the equation can be written as follows. aC6H12O6 + bO2 → cCO2 + dH2O Now, a set of equations must be formulated (between the reactant and product side) in order to balance each element in the reaction. In this example, the following equations can be formed. This system of equations can have multiple solutions, but the solution with minimal values of the variables is required. To obtain this solution, a value is assigned to one of the coefficients. In this case, the value of a is assumed to be 1. It is important to note that these equations must be solved in a manner that each variable is a positive integer. If fractional values are obtained, the lowest common denominator between all the variables must be multiplied with each variable. This is necessary because the variables hold the values of the stoichiometric coefficients, which must be a positive integer. https://byjus.com/chemistry/balancing-chemical-equations/ https://www.youtube.com/watch?v=uRnZxmCOxsI&t=26s
- B, S, Ge, At, Li
- Nuclear binding energy is the energy required to split a nucleus of an atom into its components. Nuclear binding energy is used to determine whether fission or fusion will be a favorable process. nucleon: One of the subatomic particles of the atomic nucleus, i.e. a proton or a neutron. Nuclear fission is a process where the nucleus of an atom is split into two or more smaller nuclei, known as fission products. When neutrons are released during the fission process, they can initiate a chain reaction of continuous fission which sustains itself. chain reaction: A sequence of reactions where a reactive product or by-product causes additional reactions to take place. Atomic bombs are nuclear weapons that use the energetic output of nuclear fission to produce massive explosions. Only two nuclear weapons have been used in the course of warfare, both by the U.S. near the end of World War II. Nuclear transmutation was first consciously applied to modern physics by Frederick Soddy when he, along with Ernest Rutherford, discovered that radioactive thorium was converting itself into radium in 1901. At the moment of realization, Soddy later recalled, he shouted out: “Rutherford, this is transmutation!” Rutherford snapped back, “For Christ’s sake, Soddy, don’t call it transmutation. They’ll have our heads off as alchemists.”