Chapter 2a Atoms and Bonds

atom

smallest indivisible unit of matter

matter

anything that occupies space and has mass

proton

positively charged subatomic particle found in the nucleus of an atom

electron

Negatively charged subatomic particle found orbiting the nucleus of an atom

neutron

uncharged subatomic particle found in the nucleus of an atom

molecule

two or more atoms bonded together

element

all atoms with the same atomic number

mass number

mass of protons plus neutrons in an atom

ion

atom that has more or less electrons than protons, and is therefore charged

isotope

atoms of the same element that have a different number of neutrons

atomic weight

number of protons in an atom

valence shell

outermost electron shell of an atom

octet rule

all atoms want to have full outer shells

orbital

region around the nucleus of an atom where electrons are found

covalent bond

sharing of electrons between to atoms

polar covalent bond

covalent bond in which the electrons are not shared equally, leading to partial charges in the molecule

nonpolar covalent bond

covalent bond in which the electrons are shared equally, so no partial charges occur in the molecule

electronegativity

index that tells how strongly an atom attracts electrons

ionic bond

electrical attraction between two ions

hydrogen bond

weak electrical attraction between two polar molecules

atomic number

the number of protons in an atom

anion

negatively charged ion

cation

positively charged ion