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Chap. 11-12
Science, Chapters 11-12
| Question | Answer |
|---|---|
| Matter is made of particles called atoms. | Democritus |
| An atom is the smallest particle into which an element can be divided and still be the same substance. | Democritus |
| 440 BC | Democritus |
| All substances are made of atoms | Dalton |
| atoms are small particles that cannot be created, divided, or destroyed. | Dalton |
| Negatively charged particles that are now known as electrons were discovered be | Thomson |
| Dalton | 1803 |
| Thomson | 1897 |
| Center of an atom is a tiny, positively charged atom called a nucleus. | Rutherford |
| Rutherford | 1911 |
| electrons follow a certain path or energy level around nucleus | Bohr |
| Bohr | 1913 |
| Electrons are likely to be found in | electron clouds |
| The nucleus is made of | protons and neutrons |
| outside nucelus are negatively charged particles called | electrons |
| For bigger atoms, add more... | protons, neutrons, electrons |
| The number of protons in the nucelus of that atom is the... | atomic # |
| All atoms of an element have the same | atomic # |
| What are isotopes? | atoms that have same # protons but dif. # neutrons |
| An unstable atoms has a nucelus that will... | change over time |
| You can identify each isotope by its | mass # |
| what is the mass #? | sum of protons/neutrons in an atom. |
| What is atomic mass? | the weighted average of the masses of all the naturally occuring isotopes of that element. |
| What are the four forces? | gravitational force, electromagnetic force, strong force, weak force |
| Dmirti Mendeleev | 1869 |
| Henry Moseley | 1914. Figured out atomic number worked better than mass. |
| 92 natural elements, and | 12 synthetic |
| What is the periodic law? | the repeating chemical and phyisical properties of elements change periodically with the element's atomic # |
| Metals are: | found of left side of zigzag line, solid room temp. shiny, ductile, malleable, thermal conductor |
| Nonmetals: | found right of zigzag. Not malleable, ductile. noit shiny and poor conductors. most are gases at room temperature |
| Metalloids: | border zigzag. |
| Silicon and germanium are used in: | computer chips |
| Alkali metals are reactive? | yes, they are reactive |
| Alkaline earth metals are: | less reactive than alkali metal |
| Transition metals have: | 1 or 2 electrons in outer shell, properties of metals |
| Halogens are good conductors? | No, they are not |
| Are noble gases reactive? | NO, they are stable |
| Why is hydrogen different? | It sometimes has an extra electron and sometimes has one less electron |
Created by:
Tsarmina
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