Key Terms, Key Equations, Summaries, and Exercises (Chapter 2)
Key Terms, Key Equations, Summaries, and Exercises (Chapter 2)
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Key Terms
- alpha particle (α particle)
- positively charged particle consisting of two protons and two neutrons
- anion
- negatively charged atom or molecule (contains more electrons than protons)
- atomic mass
- average mass of atoms of an element, expressed in amu
- atomic mass unit (amu)
- (also, unified atomic mass unit, u, or Dalton, Da) unit of mass equal to <span id="MathJax-Element-1410-Frame" class="MathJax" style="box-sizing: border-box; overflow: initial; display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 14px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="“>112 of the mass of a 12C atom
- atomic number (Z)
- number of protons in the nucleus of an atom
- cation
- positively charged atom or molecule (contains fewer electrons than protons)
- chemical symbol
- one-, two-, or three-letter abbreviation used to represent an element or its atoms
- Dalton (Da)
- alternative unit equivalent to the atomic mass unit
- Dalton’s atomic theory
- set of postulates that established the fundamental properties of atoms
- electron
- negatively charged, subatomic particle of relatively low mass located outside the nucleus
- empirical formula
- formula showing the composition of a compound given as the simplest whole-number ratio of atoms
- fundamental unit of charge
- (also called the elementary charge) equals the magnitude of the charge of an electron (e) with e = 1.602 <span id="MathJax-Element-1411-Frame" class="MathJax" style="box-sizing: border-box; overflow: initial; display: inline; font-style: normal; font-weight: normal; line-height: normal; font-size: 14px; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;" tabindex="0" role="presentation" data-mathml="“>× 10−19 C
- ion
- electrically charged atom or molecule (contains unequal numbers of protons and electrons)
- isomers
- compounds with the same chemical formula but different structures
- isotopes
- atoms that contain the same number of protons but different numbers of neutrons
- law of constant composition
- (also, law of definite proportions) all samples of a pure compound contain the same elements in the same proportions by mass
- law of definite proportions
- (also, law of constant composition) all samples of a pure compound contain the same elements in the same proportions by mass
- law of multiple proportions
- when two elements