Semester exam - Basic chemistry terms

Elements

a pure chemical substance that cannot be broken down into other substances

atom

the smallest unit of an element which retains all of the properties of the elements

atomic number

number of protons. does not change

mass number/atomic weight

number of protons plus number of nuetrons. it is an average, as number of protons does not change but neutrons can

isotope

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

electrons

negatively charged. fill around nucleus from inside to out.

mass of protons and neutrons

is the same

in comparison to the mass of protons and neutrons, electrons are

tiny

valence shell

outermost shell

atoms must have a full … to become stable

outershell

an ion is

an atom that has to lose or gain electrons to fill an outershell

cation

a positively charged ion with more protons than electrons

anion

a negatively charge ion with more electrons than protons. name is changed with an ‘ide’ on the end

no. protons =

no electrons in an atom

atomic weight - atomic number

number of neutrons

groups

vertical columns on the periodic table

periods

horizontal rows on the periodic table

valency

number of electrons moved for the atom to become an ion. doesn’t have + or - symbols

non-metals naming

when a non-metal becomes an ion, add ‘ide’ to the end

polyatomic ions

clusters of atoms that act as a single ion

compound

a substance made up of 2 or more different elements chemically combined

polyvalent metals

metals that have more than one valency. commonly transition metals. use roman numerals

diatomic gases.

cannot exist as a single atom on their own. Bromine, Iodine, Nitrogen, Chlorine, Hydrogen, Oxygen, Fluorine.

ionic bonding

follows the transfer of electrons from one element to another and creates an ion.

an ionic bond is made up of

a metal and a non-metal

valence electrons is the

amount of electrons in the outershell

valency

the capacity of an atom to form covalent bonds with other atoms.

properties of ionic substances

high melting points, conduct electricity, lattice structure, hard and brittle

covalent bonding

involves the sharing of electrons and is between a non-metal and a non-metal.

metallic bonding

refers to the electrostatic attraction between metal ions in a lattice structure

lattice

a regular repeating structure