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2.1 Biology
chapter 2
Term | Definition |
---|---|
matter | anything that has mass and takes up space |
mass | a measure of the amount of matter in an object; a fundamental property of an object that is not affected by the forces that act on the object, such as a gravitational force |
element | a substance that cannot be broken down or separated into simpler substances by chemical means; all atoms of an element have the same atomic number |
atom | the smallest unit of an element that maintains the chemical properties of that element |
nucleus | in physical science, an atoms central region, which is made up of protons and neutrons |
proton | 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 |
neutron | a subatomic particle that has no charge, and that is located in the nucleus of an atom |
atomic number | the number of protons in the nucleus, is the same for all atoms of an element |
mass number | the sum of the number of protons and neutrons in an atoms nucleus |
electron | a subatomic particle that has a negative charge |
orbital | a region of an atom where there is a high probability of finding electrons |
isotope | an that has the same number of protons (or the same atomic number) as other atoms of the same element do but has a different number of neutrons (different atomic mass) |
compound | a substance made up of atoms of 2 or more different elements joined by a chemical bond |
chemical bond | the attraction force that holds atoms or ions together |
covalent bond | chemical link between 2 atoms in which electrons are shared between them |
molecule | a group of atoms that are held together by chemical forces; a molecule is the smallest unit of matter that can exist by itself and retain all of a substances chemical properties |
ion | an atom, radical, or molecule that has gained or lost one or more electrons and has a negative or positive charge |
ionic bond | the attraction force between oppositely charged ions, which from when electrons are transferred from one atom to another |