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The Atom
Elements and Symbols
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C = Carbon
N = Nitrogen
O = Oxygen
Cl = Chlorine
Ba = Barium
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U=?
Cf = ?
Bk = ?
Md = ?
Es = ?
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K=
Pb =
W=
Sb =
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Co =
Cu =
Cr =
Mg =
Mn =
• Atom: basic unit of matter
– Smallest unit of matter that
individually retains the chemical
characteristics of an element
– Consists of a dense central
region, called a nucleus,
surrounded by a negatively
charged cloud
– Contains three types of subatomic
particles:
• Proton
• Neutron
• Electron
The Proton
• Charge = + 1.602×10−19 C
– Called “+1” for clarity
• Located in nucleus of atom
• Mass = 1.672 x 10–24 g
– Approx. 1 unified atomic
mass unit (u)
– 1 u = 1.66 x 10–24 g
• 1/12 the weight of a
Carbon-12 atom
The Neutron
• No charge (0 C)
• Located in nucleus
• Mass = 1.675 x 10–24 g
– Approx. = 1 u
The Electron
• Charge = –1.602 x 10–19 C
– Called “–1”
• Located outside nucleus in
an e- “cloud”
• Mass = 9.109 x 10-28g
– Approx. = 0 u
Plum Pudding Model
• J.J. Thomson
• 1904
Gold Foil Experiment
• Ernest Rutherford
• 1909
• Proved J.J. Thomson’s theory
wrong
• Evidence for existence of
protons
Evidence of Electrons
Dmitri Mendeleev
(1834-1907)
• Russian chemist
– Arranged elements in horizontal rows in
order of increasing atomic weight
– Started new rows in order to make
columns of chemicals with similar
characteristics
– Left spaces open for elements yet to be
discovered
Classification of the Periodic Table
Classification by Physical Properties
Metals
• Shiny
• Conduct electricity
• Ductile
– Can be drawn
through wires
• Malleable
(Shapeable)
• High M.P. & B.P
• Solids @ room
temp
• Except Hg
Non-Metals
• Don’t tend to
conduct well
• Not usually
ductile
• Tend to be
brittle
• Low M.P. &
B.P.
• Many are
gases at r.t.
Metalloids
• Have chemical
characteristics in
between those of metals
and non-metals
• Includes elements: B
(Boron), Silicon (Si),
Germanium (Ge),
Arsenic (As), Antimony
(Sb), Tellurium (Te),
Polonium (Po), Astatine
(At)
Classification by Electronic Properties
Alkali
Metals
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Group 1 (1A)
Li, Na, K etc.
Soft, shiny metals
Conduct heat and
electricity
• React violently with
H2O
– Form H2(g) and alkaline
(basic) solutions
Akali(ne) Earth Metals
• Group 2 (2A)
• Be, Mg, Ca etc.
• Not as reactive as Alkali Metals, but still quite
reactive
• Tend to make basic solutions when placed in
water
Transition
Metals
• Groups 3-12
• Tend to have high
densities and B.P.
• All are metals
• Often used for
electrical
conduction
• Often have vivid
colors when in
solution
– Used for pigments
Colors of Transition Metal
Compounds
Iron
Cobalt
Nickel
Copper
Zinc
Lanthanides
• Elements 57-71
– Lanthanum (La) to
Lutetium (Lu)
• Commonly used in lasers
• Can deflect UV and
infrared rays
Actinides/Actinoids
• Elements 89-103
– Actinium (Ac) to
Lawrencium (Lr)
• Only Actinium, Thorium
(Th), and Uranium (U)
occur naturally
– Others created by neutron
bombardment
• Radioactive
Groups 13(3A) – 16(6A)
• No common name
• Boundary between metals and non-metals
occurs here
• Contain elements abundant in earth’s crust,
atmosphere, and living things
• Contains the metalloids
Halogens
• Group 17 (7A)
• Love to form salts
with metals
– NaCl, KBr, CaCl2
• Like to form
diatomic molecules
– F2, Cl2, Br2
Noble Gases
• Group 18 (8A)
• Very
unreactive
• Don’t like to
bond to other
molecules
• Generally not
abundant
Diatomic Molecules
Dinitrogen (N2)
• Molecules consisting of only two atoms of either
the same or different elements
– O2
– CO
• Homonuclear Diatomic Molecule: a molecule
made of two atoms of the same element
– H2
• Heteronuclear Diatomic Molecule: a molecule
made of two atoms that are different elements
– NO
Allotropism
• The existence of multiple pure forms of an
element, in the same phase (solid, liquid, or gas),
that differ in structure
• Different forms are called allotropes
• Can exhibit varied physical properties and
chemical behaviors
• Don’t confuse allotropes with isotopes!!!
O2
O3
• Which atom does
the picture below
represent?
Atomic #
– # of protons
Atomic symbol
Atomic Mass
Atomic Weight
Mass #
Molar Mass
H
Number of
Protons
Number of
Electrons
Number of
Neutrons
C
Fe
Pd
W
Identify the atomic mass, number of protons, and number
of neutrons for the following elements.
Isotopes
• Atoms of the same element that
have different atomic masses
– Same number of protons
– Different # of neutrons
Lithium has two natural isotopes, 6Li
and 7Li, which have percent
abundances of 7.5% and 92.5%
respectively. What is the average
atomic mass of Lithium?
2) Using the percent abundances below,
calculate the average atomic mass for
Carbon
• C-12 = 98.890%
• C-13 = 1.110%
• C-14 = 0.0000000001%
3) Antimony (Sb) has two stable
isotopes, 121Sb and 123Sb with masses
of 120.9038 u and 122.9042 u,
respectively. Calculate the percent
abundances of these two isotopes
1)
Problems
Atomic Orbitals and
Electron Configurations
Atomic Orbitals
• Orbital: a specific region in an atom
thought to posses the highest probability of
containing the electron in question at any
one time
– Only hold maximum of two electrons at a time
– 4 basic types: s, p, d, f
S orbitals
• Spherical shape
• Lowest energy of the orbitals
P Orbitals
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Higher energy than s orbitals
Dumb bell shaped
Come in 3’s
px, py, pz
D Orbitals
• Higher energy than s
and p orbitals
• Double dumb bell
shape or single dumb
bell with a donut
• Come in 5’s
• dxy, dxz, dyz, dx2-y2, dz2
F Orbitals
• Higher energy than s, p, and d
• Come in 7’s
• How do we know where our electrons are?
• Electrons will seek the lowest E orbital available first
Hydrogen
1
Helium
Lithium?
Pauli Exclusion Principle: orbitals may hold up to
two electrons. The electrons must be of opposite spin
Hund’s Rule: electrons pair only after each
orbital of equal energy is occupied by a single
electron
Problems
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Determine the electron configurations for the
following atoms
1)
2)
3)
4)
5)
6)
7)
8)
9)
N
O
Ne
Na
Mg
Al
S
Fe
W
Noble Gas Abbreviation
• The electron configuration of the noble gas
that precedes the element in question is
represented by the noble gas’ bracketed
symbol
– Example: C = 1s22s22p2 = [He] 2s22p2
• Write the electron configurations for
Vanadium and Bismuth
Exceptions to the Rules
• Cr
• Cu
Review Problems
1) Which of the following is considered
qualitative data and which is quantitative?
a) Temperature
b) Creepiness
2) Juan likes to drive fast. If he regularly
speeds along at 160 km/hr, how quickly is
he going in miles/hr? In in/s?
3)
You have a box that emits a wave that has a wavelength of
5.0 x 10-7 m. Using the electromagnetic spectrum below,
predict what comes out of this box.
4) In the Macy's Thanksgiving
day parade, 2009, a Smurf
made his debut. His white
cap contained 36,763 L of
helium and it was about
1/10 of his body size. Using
this information, calculate
the volume of the entire
float. If the density of
helium is 0.000178 g/cm3,
what is the mass of the
helium for the entire float in
kg?
5) Identify which of the following are
heterogeneous mixtures and which are
homogeneous mixtures (solutions)
a)
b)
c)
d)
e)
f)
Jim Beam
Orange juice
Chicken noodle soup
7 up (fresh)
Blood
Clorox bleach
6) What are the electron configuration and orbital
box diagram for Phosphorous?
7) Which element has the chemical symbol Ag?
8) What are the electron configuration and orbital
box diagram for Ag?