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Ms. Boon
Chemistry
08.08_09.13

Atoms are the building blocks of all matter. Each
element consists of atoms. Atoms are tiny
particles which are indivisible by chemical means.

Atoms are made of three
smaller subatomic
particles: protons,
neutrons, and electrons.
Protons and neutrons
make up the positively
charged nucleus of an
atom and negatively
charged electrons rapidly
and randomly travel
around the nucleus

In today’s lab, you will build models of different
atoms in order to get more familiar with the
structure of the atom, types of atoms, and the
periodic table of elements.
Fill in this chart as we go.



Charge: Negative
Location: electron
clouds (orbitals)
Mass: 0.00005
amu (so small
don’t even worry
about it)
Electrons
Ion:
atom are
thatmuch
is charged.
smallerItthan
has an
unequal and
protons
number
neutrons.
of protons
Theyand
are
electrons.
located
in orbitals outside of the
nucleus.



Charge: Positive
Location: Nucleus
Mass: 1 atomic
mass unit
Note: an atom is
neutral when the
number of protons
is equal to the
number of
electrons



Isotope
=
atoms
of
the
Charge: no charge
same
element
with
Location: nucleus
different
numbers
of
Mass: 1 atomic
neutrons.
mass unit
Name
Location
Electron (e-) Orbitals
-1
Mass
(in amu =
atomic
mass unit)
Negligible
Proton (p+) Nucleus
+1
1
Neutron
(no)
0
1
Nucleus
Charge

What did the cashier say to the neutron as it
reached for its wallet?

…You’re free of charge!
Draw the chemical symbol and
diagram of a lithium atom.
Atomic Number = the number of protons
Average atomic mass= average mass of protons
+ neutrons in all isotopes of the element.
 To draw an atom diagram we can’t have part
of a neutron, so we will round or the problems
will have whole numbers.
Think, Pair, Share: What does the information on the periodic table
tell us about the number of protons, neutrons, and electrons in an
atom of a particular element?
Mass Number = #
protons + # neutrons
4
2
Atomic Number =
# protons
He
Element Symbol
He = Helium
Note: Find the # of neutrons
by subtracting the mass # atomic #
-- If the atom is neutral (not
charged), # protons = #
electrons
The atomic number always appears on the lower left side of the
symbol.
H
He
1
Li
2
3
Be
B
4
5
Mass numbers are written on the upper left side of the
symbol.
1
H
2
H
3
He
4
He
6
Li
7
Li
9
Be
10
B
11
B
The charge on an ion is shown on the right side of the symbol.
Cl-
Na+ Mg2+
Al3+
F-
O2-

Which of the following are isotopes of the
same element?
(A)
(B)
(C)
(D)

6 protons, 6 neutrons, 6 electrons
7 protons, 6 neutrons, 7 electrons
6 protons, 8 neutrons, 6 electrons
7 protons, 6 neutrons, 8 electrons
Answer: (A) and (C) – this is Carbon - 12 and
Carbon - 14.
• Sometimes, atoms of the same element
have different numbers of electrons.
• Atoms of the same element with different
numbers of electrons are called ions.
• When the number of protons and electrons
is different, the atom becomes charged.

Positively charged ions have more protons
than electrons
 Ex: Ca2+ (calcium ion) has 20 protons and 18
electrons
▪ 20 – 18 = 2

Negatively charged ions have more electrons
than protons
 Ex: Br- (bromine ion) has 35 protons and 36
electrons
▪ 35 – 36 = -1





13 protons, 14 neutrons, 10 electrons
1 proton and no electrons
53 protons, 73 neutrons, 54 electrons
16 protons, 16 neutrons, 18 electrons
4 protons, 5 neutrons, 2 electrons
IODINE: ~127 AMU
TELLURIUM: ~127 AMU



g/cm3
Density 6.24
Melting Point 449.51 °C
Boiling Point 988 °C



Density4.93 g/cm3
Melting point 114 °C
Boiling point 184 °C

One proton



Composed of protons (+) and neutrons
(neutral)
Atomic number = Number of protons (always
the smaller whole number!)
Mass number = Number of protons + neutrons
(always the bigger number and always a
decimal!)