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8th- Atoms and PT
8th- Atomic Structure and the Periodic Table
Term | Definition |
---|---|
atom | the smallest unit of an element |
proton | a positively charged subatomic particle that is found in the nucleus and has a mass of 1 amu |
neutron | a subatomic particle found in the nucleus that does not have an electric charge and has a mass of 1 amu |
electron | a negatively charged subatomic particle that is found in the electron cloud surrounding the nucleus and has negligible mass |
atomic mass | the sum of protons and neutrons in the atom |
atomic mass unit (amu) | the unit in which the mass of one atom is expressed |
isotope | an atom with a different number of neutrons and therefore a different atomic mass |
electron cloud | the area around the nucleus where the electrons are; it is mostly empty space |
orbitals | energy levels that electrons are arranged into |
valence electrons | the electrons in the last shell that form chemical bonds with other atoms; they are responsible for giving the element its chemical properties |
ion | an atom that has gained or lost an electron |
compound | two or more elements bonded together |
molecule | smallest piece of a compound |
mixture | two or more substances physically combined |
physical properties | describe traits or characteristics of matter, such as color |
chemical properties | describes how an atom reacts or does not react to another |
nucleus | what the center of an atom is called; where protons and neutrons are found |
complete | describes an energy level or orbital that is full of electrons |
atomic number | the name for the number of protons in an atom |
period | a row in the Periodic Table |
family | a group of elements with similar properties |
neutral | overall charge of an atom |
Lewis Structure | a diagram that includes only an element symbol and valence electrons |
diatomic molecule | made of two identical atoms bonded together |
pure substance | consists of only one kind of matter |
element | the simplest form of matter |
cation | an ion that has more protons than electrons, so it has a positive charge |
anion | an ion that has more electrons than protons, so it has a negative charge |