Atomic structure and the periodic table
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20 terms
Terms | Definitions |
|---|---|
 element | a substance that is made of only one type of atom; 92 naturally occuring elements |
| atom | the smallest part of an element that still has the properties of that element |
| Atomic structure | all atoms are made of 3 smaller particles (electrons, neutrons, and protons) |
| Nucleus | small, positively charged, central part of atom; contains protons and neutrons; most of the mass of the atom is in the nucleus; 1/100,000 the diameter of the atom |
| proton | has a positive electric charge; atomic mass= 1amu |
| neutron | no electric charge (neutral); atomic mass=1amu |
| electron cloud | area around the nucleus where electrons are found (Largest part of atom, Least mass) |
| electron | has negative charge, almost no mass; 1,800 electron=mass of 1 proton |
| u1 | atomic mass unit |
| electron energy levels | electrons "buzzing" around the nucleus occupy different distances from it; arranged in pairs; many of the properties of the elements can be explained by the number and arrangements of electrons in the energy levels of their atoms; electrons must fill lower energy levels before the higher energy levels |
| atomic number | the number of protons an atom has; identifies the element |
| atomic mass | the number of neutrons and protons that are in an atom |
| isotopes | atoms with the same atomic number (same element) BUT different atomic mass (different # of neutrons) |
| periodic table | a chart of all the elements arranged by their properties |
| Demitri Mendeleev | Russian chemist who invented the periodic chart |
| chemical families (group) | elements with similar properties are arranged in columns; have the same number of electrons in the outer shell (ex. alkali metals, halogens, noble gases) |
| malleable | able to be beaten or rolled into sheets |
| ductile | able to be pulled in to a wire (hard, shiny,conductor) |
| hydrogen | most abundant element in the universe |
| chemical activity | how easily an element reacts with other elements |
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