Transcript Elements and the Periodic Table

What is the structure of an
atom?
Can you identify the different
regions of the Periodic Table?
How are the number of
protons and neutrons of an
atom/element determined?
What are some properties by
which elements can be
classified?
*Distinguish between the
variable and controlled
parameters of a test?

Smallest particle of
element
› Nucleus
 Protons (+)
 neutrons (neutral)
 Mass of atom (amu)
› Electrons (-)
 Valence energy level
 Outer most e-
Atoms with same number of
protons
Atoms have different mass
number
Number of neutrons
changes
Atomic mass
unit (amu)
 Find the amu
and subtract the
atomic number.
 Difference=
number of
neutrons

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Arranged by
increasing mass
Arranged by atomic
number
Groups columns/vertical
› Same valence e- #
› Increasing mass
› Similar properties

Periods= rows/horizontal
› Most reactive on L
› Least reactive on R
› Transitions from
metals >nonmetals

Mendeleev 's
Completed Periodic
Table
Chemical symbol
Chemical name
Atomic number
• number of
protons in
atom
•Atomic Mass
• Average
mass of all
isotopes of
atom
• AMU

› Slinky
Physical:
› Conduct electricity &
heat
 Thermal conductivity
 Electrical conductivity
› luster = shiny
› Density= mass ÷ volume
› Malleable=
 made into shapes
 made into thin sheets
› Ductile= pulled into wire
Chemical:
• reactivityspeed &
efficiency of rxn
• Spectacular +
quick
• Corrosion- slow
wearing away
Group 1
 Highly reactive

› Lose electron

Always found as compounds
› Can be separated in lab
 pure substance=shiny

Most important
› Na, K
Li used in batteries & medicine
 Food contains

› Na, K

Group 2
› Fairly hard
› Grayish white
› Good conductor
electricity
› Lose 2 e› Most common: Mg,
Ca
 Ca= teeth, bones
 Mg= hard metal, mixed
w/ Al to make light wt.
material

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
Groups 3-12
Hard and shiny
Good conductors of
electricity
Less reactive
Never found pure in
nature
Fe found in
hemoglobin for
blood
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
Group 13-15
Found as
compounds in
nature
Most familiar: Al, Sn,
Pb


Top bubble/pull out row
Mixed w/ common metals to create alloys
› Metal mixed w/ at least one other element (metal)
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Found as compounds
Sc & Y similar traits
May be produced for strong magnets
Rare earth metals
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
Below Lanthanides
Naturally occur…
› Ac, Th, Pa, U

Laboratory made
› All others unstable
 Last only fraction of
second
› Quickly break into
stable forms


Elements with atomic
numbers > 92
Engineered in
laboratory setting
› Force neutrons into
existing nuclei

Use of particle
accelerator
› New elements
parallel new particle
accelerators
 Chemical
properties
› Gain or share e-
› Metal react
with nonmetal,
e- moves to
nonmetals
› NaCl
 (ionic bond)
› Rust
 (metal ionized)
› New substance
 Physical
Properties
› Poor
conductor of
heat and
electricity
› As solid, dull
and brittle
› 4 are gases at
room
temperature
 N, O, Fl, Cl

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
Group 18
aka Noble gas
Full valence electrons
› 8 valence electrons

Exist in Earth’s
atmosphere
› Small amounts

Un-reactive
› Laboratory synthesize
compounds

Uses…
› Neon signs
› Balloon gas
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Group 17
Very reactive
Pure substance is
dangerous
Gains eCompounds are
useful
Uses…
› Strengthen teeth
› Melt ice or snow
› Non-stick coating
› Salt
› Photographic film

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Properties of
metals and
nonmetals
Solid at room T
Brittle, hard, slow to
react
Uses…
› Computer chips
› transistors
› lasers

Vary in ability to
conduct electricity
› Dependent on
 Temp., exposure to
light, presence of
impurities

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Simplest atom
Three isotopes
No family/group
90% of universe
1% of lithosphere,
oceans,
atmosphere
Found mostly as
compound
(water)

Produces particles
› Alpha, beta, gamma
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
Move fast
Stopped by collisions
with atoms
› Alpha , paper
› Beta, aluminum
› Gamma, thick lead or
concrete


Injure skin
Uses
› Industrial, medicine
diagnose/treatment


Radioactive Decay
Filtration of
radioactive particles