| A | B |
|---|
| Democritus | person who first thought of and named the smallest piece of matter the "atom" |
| John Dalton | scientist that stated that atoms are indivisible and said that atoms of the same element are the same and atoms of different elements are different |
| J.J. Thomson | discovered the electron but his model of an atom did not have a nucleus and the electrons were stationary |
| nucleus | where most of the mass of the atom is found |
| protons and neutrons | subatomic particles found in the nucleus |
| 1 amu | mass of proton or electron |
| proton | subatomic particle with a positive charge |
| electron | subatomic particle with a negative charge that moves around the nucleus |
| atomic mass | sum of protons and neutrons in the nucleus |
| isotopes | atoms of the same element that have the same number of protons but different numbers of neutrons |
| atomic number | number of protons in the nucleus |
| electromagnetic force | how electrons are kept in motion around the nucleus |
| gravity | weakest of the four forces |
| strong force | hold protons in the nucleus together |
| energy levels | electrons are arranged ___________ |
| nucleus | center of the atom |
| energy | location of electrons depends on how much _______ they have |
| electron cloud | where electrons are found |
| quarks | small particles that makes up protons and neutrons |
| a.m.u | unit that measures the mass of subatomic particles |
| 2 | number of electrons that can be in the first energy level of an atom |
| 8 | maximum number of electrons that can be in the second energy level of atom |
| 1 a.m.u. | mass of a neutron |
| 1 a.m.u. | mass of a proton |
| positive | type of charge in the nucleus of an atom |
| electron | particle found outside the nucleus |
| neutral or no | type of charge a neutron has |
| periodic table | chart in which atoms are arranged |
| Rutherford | proposed that an atom has a dense positively charged nucleus |
| Bohr | scientist whose atomic model placed the electrons in definite orbits around the nucleus in fixed energy levels. |
| chemical and physical properties | Mendeleev grouped elements according to their ______ and _______. |
| atomic mass | Mendeleev arranged the elements in order of increasing ________ |
| valence | all elements in a column of the periodic table have the same _______ |
| Henry Mosley | person who determined the atomic numbers of the elements |
| atomic number | the modern periodic table arranges the elements in order of increasing ___________ |
| atomic numbers | the periodic law states that the physical and chemical properties of the elements are periodic functions of their ______ |
| groups/families | names for a column of elements that have similar properties |
| similar | elements within the same goup of family have ______ properties |
| period | NAME FOR A HORIZONTAL ROW OF ELEMENTS |
| active solid | first element in a period is always an extremely ______ _______. |
| malleability | property that describes how material can be hammered or rolled into flat sheets |
| ductility | property that describes how material can be pulled or drawn into a long wire |
| conductivity | ability of an object to transfer heat or electricity to another object |
| reactivity | ease and speed with which an element combines, or reacts, with other elements and compounds |
| neutron | subatomic particle with a neutral charge |
| electrons and protons | In a neutral atom, what 2 things are equal? |
| isotope | an atom with the same number of protons and a different number of neutrons from other atoms of the same element |
| Ernest Rutherford | scientist who theorized that an atom has a small, dense, positive center with electrons orbiting the nucleus |
| plum pudding | model that showed that atoms have negatively charged particles |
| valence electrons | electrons in the outermost energy level |
| noble gas | name of group that contains the highest number of elements |
| metalloid | has characteristics of both metals and non-metals |
| luster, ductility, malleability | physical properties of metals |
| corrosive, easily loses electrons | chemical properties of metals |
| B,Si, Ge, As, Sb, Te, Po, At | properties of metalloids |
| Alkalai metal | group in periodic table that is most reactive because it only has 1 valence electon |
| group number on periodic table | valence electons can be determined by ... |
