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19 terms

Chapter 3 Vocab S

Earth Science Vocab from our 9th grade Text Book.
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Element
a substance that cannot be changed , a substance that cannot be separated or broken down into simpler substances by chemical means
Atom
smallest particle of an element
Nucleus
control center of the cell
Proton
positively charged particle
Neutron
no charge
Atomic Number
the number of protons in the nucleus of an atom
Mass Number
the sum of the number of neutrons and protons in an atomic nucleus
Electron
negatively charged particle
Energy Level
place in an atom where an electron is most likely to be found
Valence Electron
an electron in the outermost electron shell
Isotopes
atoms of the same element that have different masses
Atomic Mass
total mass of the protons and neutrons in an atom, measured in atomic mass units
Radioactive
the process by which an unstable nucleus emits one or more particles or energy in the form of electromagnetic radiation
Compound
(chemistry) a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight
Chemical Bond
the attractive force that holds atoms or ions together
Covalent Bond
a bond formed when atoms share one or more pairs of electrons
Molecule
two or more atoms held together by covalent bonds
Ion
atom that has a positive or negative charge
Ionic Bond
bond formed when one or more electrons are transferred from one atom to another