chemistry-chapter1

Atom

smallest building unit of an element that cannot be broken into anything simpler

Isotopes

atoms of the same element having the same no of protons but diff no of neutrons

no of periods

= no of shells

no of groups

no of e in the outermost shell

F2 (g)

pale yellow 

Cl2 (g)

greenish yellow

Br2(l)

red brown

Br2(aq)(g)

orange red

Iodine (s)

gray

Iodine (g)

purple

Iodine (aq)

brown

At2(s)

black

Element

a substance formed of only one type of atoms having the same chemical properties and the same atomic no

Compound

a substance formed of diff elements that are chemically bonded and cannot be physically separated

Mixture

2 or more diff substances that are not chemically bonded and can be physically separated

Molecule

2 or more atoms that are covalently bonded

Diatomic molecule

2 atoms that are covalently bonded