Download The Atom, Atomic Number, Mass Number and Isotopes

The Atom, Atomic Number, Mass Number and Isotopes
 An____________ is the smallest particle of an element that retains
the properties of that element.
 The atoms of an element are ____________________ but
____________________from atoms of other elements.
Main particles of an atom
Particle
Location
Electrons
Symbol
e-
Protons
Charge
1+
Neutrons
Atomic number counts the number
11
of ________________ in an atom.
Na
Mass number measures the number of
11
Na
22.99
______________ and ______________
in an atom.
Use the atomic number and the mass number to
determine the number of protons neutrons and electrons for the following atoms.
Mass
Number
Bromine
(Br)
Fluorine
(F)
Radon (R)
Iodine (I)
Iron (Fe)
Copper
(Cu)
Atomic
Number
Protons
Electrons
Neutrons
Isotopes
 Atoms with the same number of _______________, (same atomic mass)
but different numbers of ____________
 Example: Two isotopes of chlorine
35Cl
37Cl
17
all atoms of chlorine
contain 17 protons
17
chlorine - 35
(contains 18 neutrons)
chlorine – 37
(contains 20 neutrons)
Ions

When atoms gain electrons they form _____________________ ions.

When atoms lose electrons, they form _____________________ ions.
Na+
Ion
N
a sodium atom that
has lost an electron
Protons
O2-
an oxygen atom that has
gained two electrons
Neutrons
Electrons
3-
Al3+
K+
Sr2+
Mn2+
Cl-
Mixed Practice Problems
A. An atom of zinc has a mass number of 65. What is the number of protons?
1) 30
2) 35
3) 65
B. What is the number of neutrons in an atom of zinc?
1) 30
2) 35
3) 65
C. What is the mass number of a zinc isotope with 37 neutrons?
1) 37
2) 65
3) 67