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Apologia Chem M 3A
Atomic Structure
| Question | Answer |
|---|---|
| Chemists often use things that we can see to | learn about things we cannot see. |
| Ecclesiastes 8:17 tells us, | "No one can comprehend what goes on under the sun." |
| We can use indirect observation | to help us learn about atoms. |
| Democritus | first theorized about atoms some 2,400 years ago |
| William Crookes | 1800s, English Chemist, studied how certain gases behaved when exposed to electricity |
| Crookes tube | also called a cathode ray tube |
| JJ Thomson | English Chemist, demonstrated that one of Dalton's main assumptions was wrong, discovered that cathode rays were electrically charged |
| Understanding electricity begins with understanding | the concept of the electrical charge. |
| We know how electrical charges behave and how they generate electricity, but we really don't know much about | what they are or where they come from. |
| 2 types of electrical charges | positive and negative |
| Something that does not have an overall electrical charge is electrically | neutral. |
| 2 rules of electrical charges | Like charges repel each other. - AND - Opposite charges attract each other. |
| Thomson discovered and named | electrons. |
| Ernest Rutherford, Thomson's student, discovered and named | protons. |
| James Chadwick | 1932, English scientist, discovered and named the electrically neutral neutron |
| By 1932, scientists had determined that atoms were | made up of 3 components: protons, electrons, and neutrons. |
| atomic number | tell how many protons an atom contains |
| All atoms have | an equal number of electrons and protons. |
| Isotopes are | atoms with the same # of protons but different # of neutrons. |
| Isotopes behave | identically in their chemistry. |
| The main difference between isotopes is in their | mass. |
| mass number | sum of neutrons & protons in an atom. |
| isotopic enrichment | artificially changing the ratio of isotopes within an element |
| plum pudding model | proposed by JJ Thomson, first proposed model for how electrons were believed to be found within an atom, disproved by Rutherford |
| alpha particles | positive particles emitted by certain radioactive isotopes |
| Rutherford model | planetary model of the atom, with protons clustered together in the center (called the nucleus), while the electrons orbit around the nucleus |
| nucleus | the center of the atom |