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A quantitative observation involves numbers and
measurement. A qualitative observation is
descriptive. Classify these observations:
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There are 550 students at OHS.
The sky is blue.
My car is old.
The door is 2.2 m tall.
Classify the following matter as either a pure
substance or a mixture:
1. Gold
3. Hydrogen
2. Dirt
4. Salt Water
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I can draw a diagram of an atom and label the
subatomic particles.
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I can define atomic number and mass number
and explain their relationship to subatomic
particles.
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I can use the periodic table to identify
elements and their subatomic structure.
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Catalyst
Videos about atoms!
Introduction to Atomic Structure
White Board Practice: Atom “I Spy”
Edible Atoms Lab
Exit Slip
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http://www.youtube.com/watch?v=bw5TE
5o7JtE&feature=related
http://www.youtube.com/watch?v=zGMwSKFBpo
http://scaleofuniverse.com/
…but first, a short history lesson and the story of Mr.
Rutherford, who had a little too much time…
Democritus (460 BC)
The idea of an atomic theory
is more than 2000 years old.
Ancient Greece:
Democritus: Atoms are the
Smallest indivisible particles
Plato & Aristotle: there is not
an ultimately indivisible
particle
Plato (428 BC)
Aristotle (384 BC)
Atoms Explain Gas
Properties
Proposes atomic theory
based on three scientific
laws about the properties
of matter.
Lead
block
Uranium
Flourescent
Screen
Gold Foil
What he expected
What he observed
Assumptions:
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Atom is mostly empty.
Small dense, positive
piece at center.
Rays deflected by center.
+
+
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Two regions:
 Nucleus- dense center
 Electron cloud- empty
space where you
might find an electron
 The nucleus is the dense, central portion of
the atom.
 The nucleus is made up of protons and
neutrons.
 The nucleus has all of the positive charge,
nearly all of the mass, but only a very small
fraction of the volume of the atom.
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Charge: Positive
Location: Nucleus
Mass: 1 atomic mass unit
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Charge: no charge
Location: nucleus
Mass: 1 atomic mass unit
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Charge: Negative
Location: electron
clouds (orbitals)
Mass: 0.00005
amu (so small
don’t even worry
about it)
Name
Location
Electron (e-) Orbitals
-1
Mass
(in amu =
atomic
mass unit)
Negligible
Proton (p+) Nucleus
+1
1
Neutron
(no)
0
1
Nucleus
Charge
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What did the cashier say to the neutron as it
reached for its wallet?
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…You’re free of charge!
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Number of protons determine an atom’s
identity
 # of protons= atomic social security number, it’s
different for each element.
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Mass Number = the number of protons +
neutrons.
 The mass in the nucleus.
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When the atom is neutral (no net charge), the
number of protons = number of electrons
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APEMAN
Atomic number =
Proton number and
Electron number.
Mass number –
Atomic number =
Neutron number.
IODINE: ~127 AMU
TELLURIUM: ~127 AMU
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6.24 g/cm3
Density
Melting Point 449.51 °C
Boiling Point 988 °C
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Density4.93 g/cm3
Melting point 114 °C
Boiling point 184 °C
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One proton
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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!)
“I spy an element with an atomic number of…
 25.”
 109.”
 72.”
 87.”
 1.”
 6.”
 98.”
 74.”
“I spy an element with an atomic mass of…
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83.798.”
226.”
40.078.”
4.00.”
9.01.”
39.098.”
261.”
55.845.”
Charge of a proton?
Charge of an electron?
Charge of a neutron?
Mass of a proton?
Mass of an electron?
Mass of a neutron?
Location of proton?
Location of neutron?
Location of electron?
Sometimes, atoms of the same element
have different numbers of neutrons.
Atoms of the same element with different
numbers of neutrons are called isotopes.
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Which of the following are isotopes of the
same element?
(A)
(B)
(C)
(D)
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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.
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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
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Positively charged ions have more protons
than electrons
 Ex: Ca2+ (calcium ion) has 20 protons and 18
electrons
▪ 20 – 18 = 2
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Negatively charged ions have more electrons
than protons
 Ex: Br- (bromine ion) has 35 protons and 36
electrons
▪ 35 – 36 = -1
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Catalyst
Periodic Table Song
Introduction to Atomic Structure
Atom “I Spy”
Edible Atoms Lab
Review Elements Project
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-
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You will be working with the person sitting next to you.
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Use your white board as a place mat.
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You and your partner will receive a bag of cereal to use in
this activity.
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There is no extra cereal. Do not eat the cereal until you
have finished the activity.
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Earn Class Points by keeping the cereal on your place mat.
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When you have finished all nine diagrams, raise your
hand to get a stamp!