Download Atomic Mass

Atoms and Their Masses
Unit 2, Activity 1
Active Chemistry: 1-3
Goals
 Students understand the following
concepts
 atomic mass
 Students can use their Periodic
Tables to identify
 Atomic Mass of different elements
Do Now
 What is the difference between
atomic number and atomic mass?
Do Now
 What is the difference between atomic
number and atomic mass?
 atomic number: the number of protons
in an atom
Atomic mass: the number of protons
and the number of neutrons in an atom
Objective
 I can define atomic mass and
atomic number, and explain why
atomic mass is different for every
atom in the universe using
independent practice
Agenda
1.
Do Now, Objective (5 min)
2.
Video (10 min)
3.
Atomic Mass Notes (15 min)
4.
Guided Practice (5 min)
5.
Independent Practice (20 min)
6.
Quiz 3 Retake (10 min)
The Power of Atoms
http://www.youtube.com/watch?v=-
30Yn9_6hzg&edufilter=tbARfBHuyG
3mpAruEjLFww
Quick Write – 5 min
1.
What element is the amu (atomic
mass unit) based on?
2.
Describe ‘relative atomic mass’
Atomic Mass & Atomic Number
 Atomic Mass: the mass of an atom
(# of protons + # of neutrons)
 Atomic Number: (# of protons)
Atomic number also gives you the
number of electrons in a NEUTRAL
atom
Charged atoms can have more/less
electrons
Atomic Mass
Every element has a different atomic
mass and atomic number because
every element has a different
number of protons
The size of each element depends on
the number of protons, neutrons, and
electrons it has
Hydrogen vs. Helium
HYDROGEN
Atomic Mass = 1
Atomic Number = 1
HELIUM
Atomic Mass = 4
Atomic Number = 2
Atomic Mass & Atomic Number
Magnesium
Atomic Mass = 24
Atomic Number = 12
Atomic Mass = 63
Atomic Number = 29
Label your Key – Atomic Mass & Atomic Number
How to Calculate the # of Particles
 Protons = Atomic #
 Electrons = Atomic # (if neutral atom)
 Neutrons = Atomic Mass – Atomic #
Think Pair Share
What is the atomic mass
and atomic number of
Carbon?
Carbon
Atomic Mass = 6+6 = 12
Atomic Number = 6
Think Pair Share
Carbon
How many protons does
Carbon have?
Think Pair Share
How many electrons
does Carbon have?
Carbon
6 protons & 6 electrons
Think Pair Share
How many neutrons
does Carbon have?
Carbon
# Neutrons = Atomic Mass – Atomic #
# Neutrons = 12 – 6 = 6
And the Periodic Table…
The Periodic Table increases by atomic number
Atomic # Increases towards bottom right
Atomic Mass Ratio
 Atomic Mass Ratio: the relative mass of
one element when compared to another
element (e.g. Boron: Hydrogen = 11:1)
 A boron atom is 11x heavier than a hydrogen
atom
Quick Write – 5 min
 Find the atomic mass ratio ___: ___
of the following pairs of elements –
C:Li
S:H
Ne:Fe
Cl:He
Quick Write – 5 min
 Find the atomic mass ratio ___: ___
of the following pairs of elements –
C:Li = 12:7
S:H = 32:1
Ne:Fe = 20:56
Cl:He = 35:4
Independent Practice – 20 min
 Complete the Independent Practice
with a partner
Trade & Grade – Atomic Structure Worksheet
a)
b)
c)
1
Proton (+1)
Neutron (no charge)
Electron (-1)
The number of protons in one atom an
element determines the atom’s
atomic #, and the number of electrons
determines the charge of an element
Trade & Grade – Atomic Structure Worksheet
a)
The atomic number tells you the
number of protons in one an atom of
an element. It also tells you the
number of electrons in a neutral atom
of that element. The atomic number
gives the identity of an element as
well as its location on the periodic
table. No two different elements will
have the same atomic number
Trade & Grade – Atomic Structure Worksheet
a)
The atomic mass of an element is the
total number of protons and neutrons
in the nucleus of the atom
b)
The atomic mass of an element is the
total number of protons and neutrons
in the nucleus of the atom
Trade & Grade – Atomic Structure Worksheet
a)
The atomic mass is used to
calculate the number of neutrons
in one atom of an element. In order
to calculate the number of
neutrons you must subtract the
atomic # from the atomic mass
Quiz 3 Retake
 Silently complete your quiz at your
desk
 use a calculator (not phones)