Download Foldables: Atoms

FOLDABLES: ATOMS
Terms
Atom
The basic unit of matter
It consists of a nucleus (with
protons and neutrons) and
electrons

Protons
Positively charged particles
 Found in the nucleus
 Mass: 1.0073 amu
(amu= atomic mass unit;
1amu= 1.6605 x 10^-24 g)

Neutrons
Particles found in the nucleus
 No electrical charge
 Mass: 1.0087 amu

Electrons
Negatively charged particles
 Mass: 5.4858 x 10^-4 amu
Found in a cloud outside the
nucleus

Atomic number
The number of protons in the
nucleus of an atom
In a neutral atom, the number
of protons is equal to the
number of electrons

Mass number
Sum of the number of
protons and neutrons
Mass number = protons
+ neutrons

Isotope
Atoms of the same
element that have the
same number of protons
but different number of
neutrons

Atomic weight
The average of the
masses of all the
naturally occurring
isotopes of an element

Ion
A positively, or negatively,
charged atom
Atoms become ions because
they gain or lose electrons
