ELEMENTS Group the element into four groups - gas, metal, non-metal and metal oxide.
Light and heat are included in the classification.
Johann W. Dobereiner
elements are arranged in ascending order of proton numbers Group the elements into three - a triad.
Discovers the relationship between the relative atomic mass (RAM) of the
element.
G1 G17 G18 John Newlands
Arranged the elements in order of increasing nucleon number.
The chemical properties of every eight elements are similar - law of octaves
alkali metals Also known as halogen.
Very reactive elements noble gases , inert gases monoatoms Lothar Meyer
Physical Properties :
unreactive - valence shell are full w Calculated the volume of an atom by dividing the mass we with the density of the
1- soft metals
Physical Properties electrons element.
2- low density CI gas - greenish yellow have achieved stable duplet or octet e
3- float on the surface of water Dmitri Mendeleev
Br liquid - reddish brown arrangement
4- grey shiny surface Arranged the elements in order of increasing atomic mass
Iodine solid - purplish black
5- low M.P and B.P Fl - light yellow poisonous gas(v reactive Physical Properties : Henry G.J. Moseley
6- Good conductors heat & electricity & corrosive) Insoluble in water. Bombarded different elements with high energy electrons and measured the
As - rare radioactive element Does not conduct electricity. frequency of the X-ray emitted by the element. (graph)
As going down the group Does not conduct heat.
As going down the group The boiling and melting point is
increase in atomic size. molecular size increases . increasing down the group. TRANSITION ELEMENT
Density increases. Attraction force between molecules
attraction of forces becomes stronger
The melting point decreases. stronger
& more heat energy required to Characteristics:
position of valence electrons is Boiling and melting point increases -
required to overcome the
overcome P3 High density
placed further away from the Very hard
nucleus of an atom. intermolecular forces Shiny surface
density increases with the increase Atomic radius decreases: High tensile strength
The attractive force decreases = There are only three shells, but the High conductivity
mass number of electron increases. Ductile and malleable
easily donated e Reactivity The increase in the number of High melting point & boiling point
As going down the group
Reactivity Group 17 is very reactive, the electrons = there is an increase in the
number of protons = the higher Special properties
reactivity decreases down the group. • melting point and boiling point increase - have more than one oxidation numbers
electrostatic force.
The elements will accept an electron • increase in atomic size of elements , - function as a catalyst to increase the rate of
increase attraction force between the reaction ( iron in Haber Process )
to achieve a stable octet electron The number of valence electrons - can form complex ions
arrangement. atoms atoms increases - formed coloured compound
The forces between the nucleus and
• the attraction force stronger & more heat
energy required to overcome The electronegativity increases:
the valence electron become weaker The atomic radius decreases as the
as going down the group. number of protons increases.
Helium - Used to fill weather balloons As the number of protons increases,
- Used in the oxygen tanks the electrostatic force also increases
and creates a tendency to attract
Neon - Used in advertising board lights electrons.
The left side of the period is less
Argon - Used to fill in electric bulbs electronegative
The melting point and boiling point:
Krypton - Used in flashlight of cameras Increases from the left to the middle of
alkali metal + water ->
the period, and then decrease again.
alkaline hydroxide + hydrogen gas solid -> liquid -> gas
Xenon - Used in lighthouse lamps
alkali metals + oxygen -> metal oxide ( white solid ) - Used for anesthesia metal to semi metal, and then non-
metal oxide + water -> alkaline solution metal
alkali metals + chlorine/bromine/iodine -> metal basic to amphoteric and then to acidic
Radon - Used to treat cancer
chloride/bromide/iodide Uses of semi metallic elements Uses of Transition Elements
halogen + water -> acidic solution 1- Iron, Fe -Haber Process to produce.
- have both the properties of metals and non- ammonia
halogen + metal -> metal halide metals.
halogen + alkaline solution -> metal halide + metal halate + water - weak conductors of electricity. 2- Platinum, Pt - Ostwald Process to produce
- good electrical conductors at high nitric acid
temperatures.
- silicon are used as semiconductors 3- Vanadium(V) oxide, V,O - Contact
in the manufacture of electronic microchips. Process to produce sulphuric acid
4- Nickel, Ni // platinum, Pt - hydrogenation
process on vegetable oils to produce
margarine.
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