Chapter 2 Flashcards
Atomic number
The number of protons in an atomic nucleus
Buffer
A substance that resists changes in pH
Atomic mass
The mass of an atom
Element
A substance composed of atoms having an identical number of protons in each nucleus
Dalton
British chemist who formed the atomic theory
Orbitals
A region around the nucleus of an atom with the high probability of containing an electron
Cation
A positively charged atom
Anion
A negatively charged atom
Isotopes
Different forms of the same element with the same number of protons but different electrons
Half life
The time required for something to fall to half it’s initial value
Radioactive isotopes
An isotope that is unstable and undergoes radioactive decay, releasing energy
Energy levels
A constant value of energy in the distribution of energies among a number of atomic particles
Oxidation
Loss of an electron by atom or molecule
Reduction
The gain of an electron by an atom
Molecule
2 or more atoms grouped together to form the smallest form of a substance
Valence electrons
An electron in the outermost energy level of an atom
Compound
A combination of 2 or more elements
Octet rule
Atoms of a low atomic number combined to where they end up with 8 valence electrons in there outer level
Electronegativity
A property of atomic nuclei that refers to the affinity of the nuclei for valence electrons
Non-polar convalent bonds
A bond in which a pair of electrons is distributed or shared equally between 2 atoms
Polar convalent bonds
A pair of shared electrons between 2 atoms, but the pair is held more closely by one atom
Ionic bonds
A type of chemical bonding in which one or more electrons are transferred completely from one atom to another
Hydrogen bonds
A weak association formed with hydrogen in polar covalent bonds
Surface tension
A tautness of the surface of a liquid, caused by the cohesion of the molecules of a liquid
