Atoms+Perodic table

Atoms

smallest piece of a substance

What are inside the nucleus

Protons (positive)
Neutron (neutral)

Crying baby (what do atom want)

To be electrically neutral
to have a valence shell to the nearest noble gas

Atomic number

number of protons

Mass number

protons+neutrons

Electrically neutral atom

same amount of electrons and protons → cancel out

what’s element

pure substance made up of one type of atom.
changing protons=different element

Valence electrons

outershell electrons
atoms with same amount of valence electrons react the same way
critical for chemical reactions

Periods

determine how much shells in an element

Groups

how many valence electrons
elements in the same group react the same way

octete rule

when atoms combine to form molecules, they generally each lose/gain atoms or share electrons until they attain 8

which groups are metals

1-13

which groups are non mentals

15,16,17

which groups are noble gases

18
don’t react because of their full outershell
great chemical stability