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Unit 3
Atoms and the Periodic Table
Term | Definition |
---|---|
Atom | Smallest particle into which an element can be divided and still be the same element. |
Electron | Negatively charged particles. |
Nucleus | Small dense center that has a positive charge and is surrounded by moving electrons. |
Proton | Positively charged particles in the nucleus. |
Neutron | Particles that have no charge and are neutral. |
Electron Cloud | Area around the nucleus that electrons move. |
Atomic Number | Number of protons in the nucleus of the atom. |
Mass Number | Total number of protons and neutrons in an atom. |
Periodic Table | Mendeleev's arrangement of elements. |
Average Atomic Mass | Weighted average of the masses of all the naturally occurring isotopes of that element. |
Chemical Symbol | Abbreviation for the element's name. |
Metals | Elements that are shiny and conduct heat and electricity well. |
Nonmetals | Poor conductors of heat and electricity. |
Metalloids | Elements that have some properties of metals and some of nonmetals. |
Group | Vertical column of elements. |
Period | Horizontal row of elements. |