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Atoms/ Period Table
8.5ABC
Term | Definition |
---|---|
Atom | smallest particle of an element that maintains the properties of that element |
Atomic mass | average mass number of all atoms of an element (from particles in the nucleus) |
Atomic number | the number of protons in the nucleus of an atom; used to determine an element's position in the Periodic Table |
Chemical property | a characteristic of a substance that describes how it combines with other substances to form new ones |
Electrical charge | a property of a subatomic particle; positive (protons), negative (electrons), or neutral (neutrons) |
Electron | a negatively charged particle in the electron cloud surrounding the atomic nucleus |
Electron cloud | he negatively charged space containing electrons that surrounds the atomic nucleus |
Element | a pure substance that cannot be broken down chemically into simpler substances |
Groups (families) | the vertical columns on the Periodic Table |
Mass number | total number of protons and neutrons in a specific atom |
Neutron | a (neutral) particle with no electrical charge within the atomic nucleus |
Nucleus | the positively charged center of an atom containing the protons and neutrons |
Periodic Table | a conceptual model in which the elements are organized according to their properties; often displayed as a chart |
Periods | the horizontal rows on the Periodic Table |
Physical property | property of matter that can be observed without changing the composition or identity of the matter |
Proton | a positively charged particle within the atomic nucleus; used to identify an element |
Reactivity | tendency of a substance to undergo chemical changes in a system |
Subatomic particle | a particle smaller than an atom, such as a proton, neutron, or electron |
Valence electron(s) | electron(s) located in outer energy level (electron shell) |