This document summarizes the history and development of the atomic theory and periodic table. It discusses early Greek philosophers' ideas about atoms, John Dalton's atomic theory in the early 1800s, J.J. Thomson's discovery of electrons in the late 1800s, Ernest Rutherford's discovery of the nucleus in 1909, and the discovery of neutrons in 1930 which completed the modern atomic model. It also explains how atoms are composed of protons, neutrons and electrons, how atomic and mass numbers are used to identify elements and isotopes, and how average atomic masses are calculated based on the relative abundances of isotopes in nature.
Hello Friends,
I have made this PPT especially for 10th Standard students of Maharashtra State Board (SSC). This PPT is made highly informative and illustrative, so that each and everyone of you can understand the basics of Science.
Best of Luck!
Hello Friends,
I have made this PPT especially for 10th Standard students of Maharashtra State Board (SSC). This PPT is made highly informative and illustrative, so that each and everyone of you can understand the basics of Science.
Best of Luck!
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
2. The Atom Chemistry is all about the investigation of matter and what it is. Eventually, chemists ask the question: what is matter made of? To answer that question, you need to go back 2000 yrs to a man named Democritus. Democritus believed that matter was made of a particle so small that it could not be broken any further than itself. He called this particle the atom . Aristotle, however, disagreed and downplayed this theory and so Democritus was pushed aside (and so was his theory). Democritus’ theory also didn’t explain chemical behavior so was disregarded.
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5. It wasn’t until 1803 that the concept of the atom was widely introduced again. John Dalton, an English teacher, was able to relate atoms to matter. He proposed an atomic theory: 1. All matter is composed of atoms. 2. Atoms of an element are identical in size, mass, and other properties; different elements atoms’ differ in size, mass, and other properties. 3. Atoms cannot be created, destroyed or subdivided. 4. Atoms of different elements combine in simple ratios. 5. In chemical reactions, atoms are combined, separated, or rearranged.
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7. Dalton’s theory was widely accepted for the rest of the 1800’s because it explained so many new observations of matter. The start of the 20th century saw a break down of Dalton’s theory, however. In 1903, JJ Thomson found that matter is made of negatively charged particles. The name of these negatively charged particles, originally called corpusles by Thomson, is now called electrons.
9. Because cathode rays always have the same properties, regardless of the element used to produce them, it was concluded that electrons are present in atoms of all elements.
10. After the discovery of the proton, Thomson came up with a model of the atom: This model had too many problems, however, and it would be 20 years before another one would clarify things. In 1909, Ernest Rutherford bombarded a thin sheet of gold foil w/ positively charged particles. He found that these (+) particles had no effect on the gold atoms. That can only mean the (+) charges aren’t equally surrounding the atom. This is called the raisin-filled fruitcake model. Also called “plum pudding” model.
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14. They must be in a small dense portion of the atom. And this small area must be (+) charged. The name of the positively charged area of the atom is called the nucleus . Rutherford then came up w/ a new model of the atom (which he stole from a Japanese scientist):
15. In 1930 the final part of the atom was found: the neutron. New Model: Neutrons have no charge but roughly the same mass as a proton. e - = electrons p + = protons n 0 = neutron
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17. Atomic number equals the number of protons Atoms are composed of electrons, protons, and neutrons. Protons and neutrons make up the small, dense nucleus. Electrons surround the nucleus and occupy most of the volume of the atom. How, then, are atoms of hydrogen different than atoms of oxygen? Elements are different because they contain different numbers of protons. The atomic number, Z, tells you how many protons are in an atom.
18. Remember that atoms are always neutral because they have an equal number of protons and electrons. Therefore, the atomic number also equals the number of electrons the atom has . Each element has a different atomic number . For example, the simplest atom, hydrogen, has just one proton and one electron, so for hydrogen, Z = 1. The largest naturally occurring atom, uranium, has 92 protons and 92 electrons, so Z = 92 for uranium. The atomic number for a given element never changes.
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20. Mass number equals the total number of subatomic particles in the nucleus The mass number, A , of an atom equals the number of protons plus the number of neutrons. A fluorine atom has 9 protons and 10 neutrons, so A = 19 for fluorine. Oxygen has 8 protons and 8 neutrons, so A = 16 for oxygen. This mass number includes only the number of protons and neutrons (and not electrons) because protons and neutrons provide most of the atom’s mass. Although atoms of an element always have the same atomic number, they can have different mass numbers.
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22. Calculating the number of neutrons in an atom Atomic numbers and mass numbers may be included along with the symbol of an element to represent different isotopes. The two isotopes of chlorine are represented below. If you know the atomic number and mass number of an atom, you can calculate the number of neutrons it has.
23. Mass number ( A ) - Atomic number ( Z ) = # of neutrons
24. Isotopes of an element have different numbers of neutrons Neutrons can be added to an atom without affecting the number of protons and electrons the atom is made of. Many elements have only one stable form, while others have different “versions” of their atoms. Each version has the same number of protons and electrons as all other version but a different number of neutrons. These different versions, or isotopes , vary in mass but are all atoms of the same element because they each have the same number of protons. Three isotopes of hydrogen exist and have the same chemical properties because each is made of one proton and one electron.
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26. Atomic Mass The mass of a proton or neutron is very small; an electron even smaller still. The mass of the largest atom is still incredibly small, because of its components. In determining the masses of atoms, and not having to work with the incredibly small masses of protons, etc., scientists used a reference isotope as a standard. The isotope of carbon was chosen, carbon-12. The isotope of carbon was assigned a mass of exactly 12 atomic mass units.
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28. An atomic mass unit (amu) is defined as one-twelfth the mass of a carbon-12 atom . (For comparison, a helium-4 atom, with a mass of 4.0026 amu, has about one-third the mass of a carbon-12 atom.) A carbon-12 atom has six protons and six neutrons in its nucleus, and its mass is set as 12 amu. Therefore the mass of a single proton or single neutron is about one-twelfth of 12 amu, or 1 amu. You might predict, then, that the atomic mass of an element should be a whole number. However, that is not usually the case. For example, the atomic mass of chlorine (Cl) is 35.453 amu. How can this be decimal mass be explained? The atomic mass of an element is a weighted average mass of the atoms in a naturally occurring sample of the element.
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31. Example: Copper consists of 69.17% copper-63 (amu of 62.939 u); and, copper-65 which is 30.83% (64.927 u). The average atomic mass is: (.6917 x 62.939 u) + (.3083 x 64.927 u) = 63.55 u Example: An element has two naturally occurring isotopes. They have the following abundances: 50.69% (78.92 amu), and 49.31% (80.92 amu). What is the average atomic mass? (.5069 x 78.92) + (.4931 x 80.92) = 79.90 u