click below
click below
Normal Size Small Size show me how
8th Science U3
Introduction to Chemistry
| Term | Definition |
|---|---|
| nucleus | an atom's central region, which is made up of protons and neutrons |
| protons | a subatomic particle that has a positive charge and that is located in the nucleus of an atom; the number of protons in the nucleus is the atomic number, which determines the identity of an element. |
| electrons | a subatomic particle that has a negative charge |
| neutrons | a subatomic particle that has no charge and that is located in the nucleus of an atom |
| electron cloud | a region around the nucleus of an atom where electrons are likely to be found. |
| atomic number | the number of protons in the nucleus of an atom; the atomic number is the same for all atoms of an element. |
| mass number | the sum of the numbers of protons and neutrons in the nucleus of an atom. |
| atom | the smallest unit of an element that maintains the properties of that element. |
| periodic table | an arrangement of the elements in order of their atomic numbers such that elements with similar properties fall in the same column, or group. |
| chemical symbol | a one-, two-, or three-letter abbreviation of the name of an element |
| average atomic mass | the weighted average of the masses of all naturally occurring isotopes of an element |
| metal | an element that is shiny and that conducts heat and electricity well. |
| nonmetal | an element that conducts heat and electricity poorly |
| metalloid | an element that has properties of both metals and nonmetals. |
| group | a vertical column of elements in the periodic table; elements in a group share chemical properties. |
| period | a horizontal row of elements in the periodic table. |
| chemical bond | an interaction that holds atoms or ions together. |
| valeence electron | an electron that is found in the outermost shell of an atom and that determines the atom's chemical properties. |