Periodic trends
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1) Before 1860, there was no standard system for determining atomic masses or numbers, leading to inconsistencies in proposed chemical compositions. 2) In 1860, Italian chemist Stanislao Cannizzaro presented a convincing method for accurately measuring atomic masses, which was agreed upon by chemists. 3) As you move from the upper-right to the lower-left of the periodic table, the size of atoms generally increases due to additional electrons being added as atomic number increases down groups and nuclear charge pulling electrons closer as atomic number increases across periods.
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period) generally have a lower electron affinity than nonmetals (right side of a period) with the
exception of the noble gases.
Hope this explains your daughter.... :)
Solution
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3. The periodic table is arranged into rows called periods and columns called groups. Each element square provides the symbol, name, atomic number and other properties. Valence electrons are important for determining chemical properties and are indicated by the group number.
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This document provides two chemical reactions and asks questions to determine the limiting reactant, mass of products formed, and excess reactant remaining. The first reaction involves ammonium nitrate and sodium phosphate. The second reaction involves calcium carbonate and iron (III) phosphate. For each reaction, the document asks what reactant is limiting given specific starting masses, the mass of each product that can be formed, and the mass of any excess reactant left over.
Do now end of ch 6 im_fs
1. Chemical bonds result from the mutual attraction between nuclei and electrons.
2. Polar covalent bonds are likely to form between atoms that differ in electronegativity.
3. The Lewis structure of HCN contains one triple bond and one single bond.
Thermochemistry ch 16
This document provides an overview of thermochemistry and key concepts related to heat and energy transfers during chemical and physical processes. It defines important terms like heat, temperature, enthalpy, and heat capacity. It also distinguishes between endothermic and exothermic reactions, and describes heat changes associated with phase changes like melting, vaporization, solidification, and condensation. Specific concepts covered include Hess's law of heat summation, standard heats of formation and reaction, and calculating heat changes using thermochemical data.
Chapter 9 moles, equations, and stoichiometry
This document provides an overview of moles, equations, and stoichiometry. It discusses converting between moles and numbers of atoms or molecules using molar mass. It gives examples of calculating moles from atoms and vice versa. It also covers using a balanced chemical equation and mole ratios to determine quantities in a chemical reaction. Finally, it discusses using molar mass and moles to determine mass for a sample of a compound.
Hydrocarbon nomenclature
Naming Hydrocarbons document provides information on naming hydrocarbon compounds according to IUPAC rules. It discusses:
1) Drawing condensed structures and choosing a naming method that shows all hydrogen atoms.
2) The basic naming of hydrocarbons based on type (-ane, -ene, -yne), number of carbons, side chain type and position.
3) Rules for numbering carbons in compounds with multiple bonds or branches to determine IUPAC names in a systematic manner.
Hess's law
Hess's law states that the total enthalpy change for a reaction is independent of the pathway between the initial and final states. To calculate the enthalpy change of a reaction, standard enthalpy change values can be used for the elementary steps that add up to the overall reaction through algebraic manipulation. For the reaction of 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g), using standard enthalpy change values for the elementary steps gives an overall exothermic enthalpy change of -906.3 kJ.
Percent comp_empirical formula_molecular formula
This document provides information and examples for calculating percent composition, empirical formulas, and molecular formulas of compounds. It defines key terms like percent composition and empirical formula. It then works through examples of calculating the percent composition of magnesium and oxygen that form a compound, the percent composition and mass of carbon in propane, and determining empirical formulas from elemental percentages or mole ratios. The document explains how to calculate molecular formulas from empirical formulas and molar masses. Finally, it provides practice problems for the reader to work through.
Unit 1 - Data Analysis
This document discusses measuring volume and temperature. It explains how to measure the volume of liquids using a graduated cylinder and the volume of irregular solids using water displacement. It introduces the SI units for length, mass, volume, temperature and density. It also covers significant figures and calculating measurements to the proper number of significant figures based on the precision of the original values.
Redox
This document discusses redox (reduction-oxidation) reactions. It defines oxidation as the loss of electrons and reduction as the gain of electrons. It explains how to identify oxidizing and reducing agents, assign oxidation numbers, and balance redox reactions using the half-reaction method. Key steps include writing separate half-reactions for oxidation and reduction and adjusting coefficients to balance the number of electrons lost and gained. Disproportionation reactions are also introduced, where a substance acts as both an oxidizing and reducing agent.
Intro acids and bases
This document defines acids and bases and their key characteristics. Acids release H+ ions in water and have sour tastes, while bases release OH- ions in water and feel slippery. Strong acids and bases fully dissociate in water, while weak ones only partially dissociate. Common strong acids include sulfuric acid and hydrochloric acid. When acids and bases react, they undergo a neutralization reaction where water and a salt are formed. Indicators are used to test whether a solution is acidic or basic. The pH scale measures the concentration of H+ ions, with lower pH indicating more H+ ions and higher pH less H+ ions.
Chapter 10 – states of matter
The document discusses the three main states of matter - solids, liquids, and gases. It explains the kinetic molecular theory and how it applies to each state. Key points include:
1) Solids have a definite shape and volume, with particles tightly packed in an ordered structure.
2) Liquids have a definite volume but fill the shape of their container. Their particles are closer than gases but still have motion.
3) Gases fill their container completely and have particles with random, rapid motion that are far apart with no intermolecular forces between them.
The document then goes into more details about the properties and characteristics of each state, phase changes, and concepts like vapor pressure
Midterm review 2013
This document contains a midterm review covering multiple physics topics including waves, electricity, and magnetism. It includes questions about key terms, concepts, equations, examples, and challenges related to each topic. Students are asked to define terms, compare examples, solve equations, draw diagrams, and review past worksheets and exams. The review is intended to reinforce important information and test the students' understanding of several chapters in preparation for the midterm exam.
Ch 8 balancing chemical reactions
This document provides information about balancing chemical equations. It begins by defining key terms like reactants, products, and catalysts. It explains how to write skeleton and balanced chemical equations, and how to balance equations by ensuring the same number and type of atoms are on both sides of the reaction. The document also describes different types of chemical reactions like synthesis, decomposition, single and double displacement, and combustion. It discusses writing and balancing net ionic equations in aqueous solutions. The overall purpose is to teach how to identify reaction types and write balanced chemical equations.
Chapters 6
This document provides an overview of chemical bonding concepts covered in Chapter 6, including:
1) Valence electrons and how to determine them from the periodic table.
2) The main types of chemical bonds - ionic, covalent, and metallic. Ionic bonds form between metals and nonmetals, covalent between nonmetals, and metallic within metals.
3) Key characteristics of ionic and covalent bonds such as crystal structure, conductivity, and bond strength. Lewis structures are used to represent covalent bonds.
Nuclear chem ppt
1. Nuclear fission is the splitting of atoms, usually large unstable atoms, which releases energy. Fission reactions have three steps: initiation, propagation, and termination.
2. Half-life is the time it takes for half of a radioactive sample to decay. The rate of radioactive decay depends only on the concentration of the radioactive isotope.
3. Nuclear fusion is the combining of small nuclei, such as two hydrogen nuclei fusing to form a helium nucleus. Fusion occurs in stars and is difficult to achieve on Earth.
Notes hydrocarbon nomenclature-side chains
The document discusses the rules for naming hydrocarbons according to IUPAC nomenclature. It explains that the root or parent chain is the longest chain that can include any double or triple bonds. Side chains are called alkyl groups like methyl or ethyl. Numbers are assigned to the carbons in the parent chain with double or triple bonded carbons numbered first consecutively. The name of each side chain is determined and attached alphabetically to the parent name along with its carbon position. Identical side chains are grouped using prefixes. An example demonstrates applying the rules to name a hydrocarbon with multiple side chains.
Chapter 14
This document discusses acids and bases. It defines acids as compounds that increase the concentration of hydrogen ions (H+) in aqueous solution, and bases as compounds that increase the concentration of hydroxide ions (OH-). Strong acids and bases completely ionize in water, while weak acids and bases only partially ionize. Different acid theories are also introduced, including Arrhenius, Brønsted-Lowry, and Lewis definitions of acids and bases. Common strong and weak acids and bases are listed.
Chapter 12 solutions and molarity
The document defines types of solutions and solubility, explains factors that influence the rate at which a solute dissolves, and describes how to calculate molarity by taking the number of moles of solute dissolved per liter of solution. Molarity is important as it allows solutions of known concentration to be prepared and diluted in predictable ways. Temperature, pressure, particle size, and agitation can impact solubility and dissolution rates.
Chapter 11 (new)
This document discusses the behavior of gases through summarizing the kinetic molecular theory and gas laws. It describes five assumptions of the kinetic theory, including that gas particles are in constant random motion and collisions are perfectly elastic. It then discusses how temperature, pressure, volume, and number of moles are related for a gas based on the gas laws of Boyle, Charles, Gay-Lussac, combined, and ideal gases. It provides examples of using the gas laws to solve problems involving changes in pressure, volume, temperature, or number of moles of a gas.
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Periodic trends
- 1. Chapter 5: The Periodic Law A brief history of the periodic table (put on your fun hats) : Before 1860, more than 60 elements had been discovered. At that time, there was no way to know the atomic mass or atomic number of the known elements, nor was there a way to know the number of atoms in a particular compound. Different chemists used different atomic masses for the same elements, resulting in different compositions being proposed for the same compounds. Madness! Damn you, chemistry! You do not equal awesome!
- 2. Chapter 5: But wait! In September of 1860, a group of chemists assembled at the First International Congress of Chemists in Germany to settle these issues once and for all. Italian chemist Stanislao Cannizzaro presented a convincing method for accurately measuring atomic masses, and everyone agreed on it. Partying ensued. Perhaps I was harsh. I’m sorry, chemistry. You’re still not awesome.
- 3. Trends in Atomic Radii Generally Decreases Generally Increases
- 4. Trends in Atomic Radii So you could sum up the general periodic trend of atomic radii like so: As you go from the upper-right to the lower-left of the periodic table, the size of the atoms increases.
- 5. Trends in Atomic Radii Generally Decreases Generally Increases
- 6. Trends in Atomic Radii (cont’d) Group Trends : Atomic size generally increases as you move down a group of the periodic table because of the additional electrons added as you increase in atomic number. Periodic Trends : Atomic size generally decreases as you move from left to right across a period. The principle energy level remains the same, only another electron is added as you move right. The effect of increasing nuclear charge on the outermost electrons is to pull them closer to the nucleus.
- 7. Trends in Atomic Radii (cont’d) When an atom gains or loses an electron, it becomes an ion . Ionization Energy : The energy required to overcome the attraction of the nuclear charge and remove an electron from a gaseous atom. Removing an electron(s) results in a positive ion, or cation . Adding an electron(s) results in a negative ion, or anion . Electronegativity : of an element is the tendency for the atoms of the element to attract electrons when they are chemically combined with atoms of another element. Each element is assigned an electro- negativity number in units of Paulings.
- 8. Trends in Ionic Radius Cationic and anionic radii decrease across periods and increase down groups Cations Decrease Anions Decrease Generally Increases
- 9. Electronegativity The strength of electronegativity tends to increase as you go up and to the right on the periodic table.