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Chemistry Chapter 4
| Question | Answer |
|---|---|
| Isotopes are basically... | Different versions of the same atom |
| Which has a charge? Atoms or ions? | Ions have a charge. Atoms are always neutral because they have an equal number of protons and electrons. |
| Isotopes have the same number of ____, but a different number of ____. | Protons; neutrons. If isotopes had a different number of protons, they would be a different element entirely. |
| The number of protons is also the _____ _____. | Atomic number |
| The mass number is equal to the number of ____ plus the number of ____ combined. | Protons; neutrons |
| Conclusions from Dalton's work: atoms react in ___ ____; mass is ____ in chemical reactions | Fixed ratios; conserved |
| JJ Thomson's ____ ____ experiment showed that there were _____ particles. | Cathode ray; subatomic |
| Rutherford's Gold Foil experiment | |
| 1. Shot alpha particles (____ atoms) at gold foil screen. | Helium |
| 2. Most particles went ____ the foil because the atom was mostly ____ space, but some ____. | Through; empty; deflected |
| 3. Deflection was caused because some particles hit the _____. | Nucleus |
| 4. Rutherford is credited to the _____ of the _____. | Discovery; nucleus |
| 5. Concluded that atoms have a ____ packed center surrounded by _____, and that most of the atom is _____ space | Densely; electrons; empty |
| Protons | -In the nucleus -Positive charge (1+) -Relative mass = 1 |
| Electrons | -Around the nucleus -Negative charge (1-) -Relative mass = 1/1840 |
| Neutrons | -In the nucleus -Neutral charge (0) -Relative mass = 1 |
| What is mass number? | Mass number = protons + neutrons |
| What is atomic number? | Atomic number = the number of protons. The atomic number is equal to the number of protons/electrons in atoms. |
| When there is a positive symbol (+) in notation, that means that the element is ____ an electron. | Losing |
| Why aren't the mass numbers on the periodic table whole numbers? | Because the average atomic mass is a weighted average of all the different isotopes of an element. |
| 1 AMU = | 1/12th the mass of a Carbon-12 atom |
| What is radioactivity? | Particles and rays (that alter an atom's identity) are emitted by unstable atoms |
| Radioactive decay: | The process of emitting rays and particles to become more stable |
| Alpha decay: | -The emission of an alpha particle (He atoms) - 4 over 2 He -Process continues until atom reaches stability |
| Beta decay: | -The emission of a beta particle (an electron) -0 over -1 e |
| What makes an atom stable? | -The ratio of protons to neutrons -Once stability is reached, the atom stops decaying |
| Loss of electrons makes the atom more ____ charged. | Positively |
| Gaining of electrons makes the atom more ____ charged. | Nnegatively |
| A positively charged atom is called a _____. | Cation |
| A negatively charged atom is called a ______. | Anion |
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