Chapter 13 - Periodic table
Keywords
Group = vertical
Period = horizontal
Valence e- = Valency
Electron shell = the outside part of an atom around the atomic nucleus
Alkali metals
Noble gases
Stable configuration
Transition metals
Electronegativity = The ability of an atom to attract a shared pair of electrons in its combined state
Non-metals are more electronegative.
Electropositivity = The ability of an atom to withdraw a shared pair of electrons in its combined state.
Metals are more electropositive
GROUP
I
II
III
IV
V
VI
VII
VALANCE
1
2
3
4
5
6
7
OXIDATION NO.
1+
2+
3+
±4 (-)
3-
2-
1-
Name of the eight groups in the periodic table:
Alkali metals.
Alkaline earth metals.
Rare earth metals.
Crystallogens.
Pnictogens.
Chalcogens.
Halogens.
Noble gases
Chapter 13 - Periodic table
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Alkali metals - Group 1
physical properties:
chemical properties
shiny, soft
soluble in water
low density
oxidize easily
low melting point
reacts with water easily
low boiling point
forms colorless compounds
they float on water
positive ions
forms ionic compounds
which elements:
trends down the group
Group 1
→ Reactivity increase down the group
Calcium
→ Melting point/ Boiling point generally decrease
Barium
→ Softer (easier to lose electrons - easy to react)
Magnesium
→ Density increases down the group (more protons)
→ Metallic character increases (how easily electrons
move)
Halogens
physical properties
chemical properties
covalent bonds
forms negative ions
poisonous gases
reactive non-metal
very low melting point
forms diatomic molecules
colored (darker down the group)
low density
which elements
trends down the group
F - yellowish green
melting point/boiling points increases
Cl - green
colors darken
Br - red brown
reactivity decreases
I - grey black solid
The inner shells shield the nucleus from
attracting e- (from alkali metals)
At - black solid
The group I metals are also called alkali metals. They react readily with water to produce hydrogen gas and an alkaline
solution of a metal hydroxide. Their reactivity increases going down the group. Lithium fizzes slowly on the surface of the water
but potassium fizzes rapidly
Element
Melting Point (’C)
Boiling Point (’C)
Physical State
Fluorine
220
-188
gas
Chlorine
-101
-35
gas
Bromine
-7
59
liquid
Iodine
+114
184
solid
Chapter 13 - Periodic table
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Reactivity and electron structures
1. The atoms get bigger as you go down the group. This reduces the attraction of the (+) nucleus for an additional (-) electron.
2. ‘Shielding’ by the inner electron shells also reduces the attraction from the nucleus. As we go down the group the tendency
to gain electrons
Displacement theory
A more reactive halogen will displace a less reactive halide from its compounds in solution.
The attraction of halogens for an extra electron gets greater going up the group: I<Br<Cl<F.
If we mix a metal halide with a more reactive halogen, the electron will be transferred from the less to the more reactive
halogen.
Reactions with metals
The attraction of halogens for an extra electron means that they readily react with most metals.
Chlorine reacts readily with iron on gentle heating despite iron’s low reactivity.
Reactions with non-metals
With metals they gain electrons forming ionic
compounds.
With non-metals they react by sharing electrons and
forming covalent compounds.
hydrogen and chlorine form hydrogen
chloride.
Fluorine
Chlorine
Bromine
Processing uranium nuclear fuel
pesticides and weed killer
leaded petrol (being phased out)
Toothpaste to prevent tooth decay
antiseptics and disinfectants
photography
Teflon- fluorine-containing polymer
HCl
agriculture
Fluoridation of water
Chlorinated carbon compounds
medicines
solvents and plastics (PVC)
Drinking water treatment
Bleach kills bacteria and makes
paperwhite
Iodide
animal feed supplements
antiseptic
13.2 | summary questions
1. The group I metals are also called alkali metals. They react readily with water to produce hydrogen gas and an alkaline
solution of a metal hydroxide. Their reactivity increase going down the group. Lithium fizzes slowly on the surface of the
water but potassium fizzes rapidly and the hydrogen produced catches fire.
2. 680
℃
3. 2Na + 2H2O → 2NaOH + H2
Chapter 13 - Periodic table
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13.3 | summary questions
1. We call the group VII elements halogens. Group VII elements have diatomic molecules. Their reactivity decreases going
down the group. At r.t.p chlorine is a yellow-green gas, bromine is a red-brown liquid and iodine is a grey-black solid
2. Because chlorine is more reactive than bromine
3. Cl2 (aq) + 2KBr (aq) → 2KCl + Br2
Noble Gases
physical properties
chemical properties
low density (less dense than air - floats)
unreactive (inert)
non-metallic
highly stable
low MP/BP (obviously it's gas)
full valency
very low mass
non-flammable
conducts electricity
odorless gases
gases at room temperature
resistant to metal corrosion
no ductility - malleability - sonorous
low toxicity
colorless
forms a single atom molecules
trend down the
group
Helium
in ballons
as the density
increases
reactivity
Neon
lighter than air - floats
coolant due to its low boiling point.
Used in advertising signs
Neon produces an orange-glowy color
when electricity passes through
Only the orange/red color contains
used in conducting coils to turn them into a
superconductor
decreases
MP/BP
increases
pure neon
Other colors contain different gases
and chemical coatings on the tubes
Krypton
reactive enough to react with fluorine
used in lasers to manufacture semiconductors
and integrated circuit boards
krypton lasers are also used in eye surgery
Argon
used as a protective atmosphere when
producing reactive metals
used as inert protective shield around hot
metals when welding it
low energy bulbs and fluorescent bulbs
gives an ultraviolet light
used to fill the space between double
glazed windows
Sources of Noble Gas
All noble gases present in the atmosphere
They are obtained through fractional distillation or liquefaction
Obtained naturally
Radon is usually isolated - this is a product of the radioactive decomposition of the radium compound
Chapter 13 - Periodic table
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Group 4
⤷ metalloids
trend down the group
half metal half non-metal
density increases
properties
MP/BP increases
0 oxidation number
more electropositive
The ionization energies decrease down the group
although there is a slight increase in lead. The trend
exists because: The atoms are getting bigger
because of the extra layers of electrons. The farther
the outer electrons are from the nucleus, the less
they are attracted; therefore, they are easier to
remove.
Group 6
properties
trends down the group
2- ions (gains 2e-)
reactivity decreases
They are less toxic in nature.
BP/MP increases down the group
They have high electronegativity.
easier to gain e-
Alkali metals
Transition metals
Softness
Soft
Hard
Density
Low
High
Reactivity
High
Low
Solubility of the compound
Highly soluble
Most insoluble
Colors of the compound
White (silver)
Colored
Uses
Battery, Fertilizers, Soda (baking, washing)
Electrodes (inert), Catalyst, Structures
Oxidation no.
1+
> 1+
Groups
Group I (Earth alkali → group 2)
Group transitions
Transition metals
physical properties
hard strong
high density
malleable and ductile
shiny
high MP/BP
except mercury which is liquid at room temperature
chemical properties
all transition metals lose electrons when they react to
form positive ions.
most transition metals can form more than one type
of ion: Iron (II) Iron (III)
reduced reactivity across the period
tend to react relatively slowly (less reactive than Goup 1)
with air and water (except iron) and acid
good conductors of heat and electricity.
Chapter 13 - Periodic table
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Iron
Titanium
hard - strong - abundant, and not
too expensive.
steel(alloy) used in
construction and engineering
Copper
as strong as steel but much
lighter, and is very
resistant to corrosion.
aerospace industry - artificial
unreactive with water
used in plumbing
good electrical conductivity
used in wires and cables
joints
Rusting is an oxidation reaction
between iron, oxygen, and water. It is a
type of corrosion. 2Fe2O3.H2O
reacts slowly with gases and water
Titanium dioxide
is a brilliantly white compound
in the air to create a thin green
layer of copper compounds.
used in paints, plastics, paper,
and toothpaste.
iron + water + oxygen → hydrated
iron(III) oxide
prevents the rest of the copper
from reacting
used as a roofing material.
Alloys
Steel is an alloy of iron and other elements, such as carbon, nickel, manganese, and chromium.
There are many different types of steel, each with different properties.
Brass is an alloy of 70% copper and 30% zinc.
Bronze is an alloy of 90% copper and 10% tin.
Cupronickel is an alloy of 75% copper and 25% nickel
it is used in ‘silver’ coins.
Identifying transition metal ions
Cation test
The presence of transition metal ions in a solution can be tested by adding sodium hydroxide solution. If they are
present, a metal hydroxide is formed.
This is insoluble so it appears as a solid called a precipitate.
Cu2+ ions produce a blue precipitate of Cu(OH)2
Fe2+ ions produce a grey/green precipitate of Fe(OH)2
Fe3+ ions produce an orange/brown precipitate of Fe(OH)3
Colors
⤷ bright coloring in children's toys is harmful as transition metals are toxic.
iron (II) compounds = usually green
Uses
iron (III) compounds = orange/brown
stained glass windows
copper (II) compounds = blue
paint
copper (II) sulfate = can be turned white by heating
the crystals to remove the water.
Chapter 13 - Periodic table
glazes on pottery
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Thermal Decomposition
Compounds of transition metals can be broken down into simpler substances by heating them.
The reactants and products are different colors.
⤷ iron(III) carbonate → iron oxide + carbon dioxide
Catalyst
Titanium is a catalyst in the production of plastics.
Nickel is a catalyst in the production of margarine (hydrogenation of vegetable oils)
Iron is a catalyst in the production of ammonia from nitrogen and hydrogen (the Haber process)
Platinum is a catalyst in catalytic converters to reduce levels of polluting gases. It speeds up the conversion of carbon
monoxide and nitrogen oxide to carbon dioxide and nitrogen.
Chapter 13 - Periodic table
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