Chemistry - compounds, formulae and equations

number of electrons in the outer shell…

relate to the group number

elements in each group…

all have the same number of electrons in their outer shell

all elements in each group have similar…

chemical properties as it is these outer electrons that take part in chemical reactions

number of shells relate…

to the period number

inert gases (noble or rare gases) have a…

complete outer shell

moving from left to right across the periodic table, the elements change…

from metals to non metals

what is silicon caleld

semi-metal or metalloid

where are transition metals found

between group 2 and 3

what do metals form

positive ions as they lose outer electrons

what do non-metals form

negative ions as they gain electrons into their outer shell

ion definition

species in which the number of electrons is not equal to the number of protons so has an overall charge

salts

compounds made up of ions, neutral, contain at least one anion and one cation

phosphate

PO₄^3-

nitrate

NO₃^-

nitrite

NO₂^-

sulfite

SO₃^2-

sulfate

SO₄^2-

spectator ions

some species which remain the same before and after the reaction so play no part in it

ionic equations useful for simplifying…

precipitation reactions and acid-base reactions