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SPM Chemistry Form 4 Notes – Periodic Table of Elements (Part 1)
Development of the Periodic Table
Periodic Table
A) Antoine Lavoisier (1743 – 1794) – French chemist
Elements were classified into 4 groups
Limitation – some wrong information (light and heat were consider as elements
B) Johann Dobereiner (1780 – 1849) – German chemist
Elements were classified into groups named as triad (Triad Law – relationship between
properties and atomic masses of the elements)
Limitation – few elements were classified
C) John Newlands (1837 – 1898) – British chemist
Elements were arranged horizontally in ascending order of their atomic masses and each row
consisted of 7 elements (Law of Octaves – same properties were repeated at every eight
element)
Limitation – obeyed by the first 17 elements only (from H to Ca)
D) Lothar Meyer (1830 – 1895) – German chemist
Properties of the elements were in a periodic pattern with their atomic masses
Similar chemical properties occupied the same relative positions on the curve
E) Dmitri Mendeleev (1834 – 1907) – Russian chemist
Elements were arranged in ascending order of their atomic masses
Elements with similar chemical properties were placed in a group
Gap for undiscovered elements
Prediction: gallium, scandium and germanium (discover later)
Separate groups for certain elements: transition elements
Meedeleev’s Periodic Table was used as a basis for the formation of the Periodic Table
F) H. J. G. Moseley (1887 – 1915) – British physicist
Elements were arranged horizontally in ascending order – proton numbers
Elements with the same number valence electrons – same group
18 vertical columns – Group 1, Group 2, until Group 18
Alkali metal – Group 1
Alkaline earth metal – Group 2
Transition elements – Group 3 to Group 12
Halogen – Group 17
Noble gas – Group 18
Horizontal row of the elements – period
Period 1 – 2 elements
Period 2 and 3 – 8 elements
Period 4 and 5 – 18 elements
Period 6 – 32 elements
Period 7 – 27 elements
Lantanides – proton numbers 58 to 71
Actinides – proton numbers 90 to 103
Elements (Group 1, 2 and 13) – metal
Transition elements (Group 3 to 12) – metal
Elements (Group 15, 16 and 17) – non-metal
Carbon and silicon (Group 14) – non-metal
SPM Chemistry Form 4 Notes – Periodic Table of Elements (Part 2)
Relationship between the electron arrangement of the atom of an element to its group and
period
The number of valence electrons determines the chemical properties of elements (group).
Elements in the same group have the same number of valence electrons.
The number of shells occupied with electrons in an atom determines the period number of an
element. Group 1 Group 2Period 2 Lithium / Li / 2.1 Beryllium / Be / 2.2Period 3 Sodium / Na / 2.8.1 Magnesium / Mg / 2.8.2Period 4 Potassium / K / 2.8.8.1 Calcium / Ca / 2.8.8.2
Group 18 elements
Monoatomic gas
Group 18 elements are known as noble gases (inert chemically and chemically unreactive).
Atomic radius (atomic size) – increases (going down the group)
Helium atom has only one filled electron shell which is 2 electrons (duplet electron
arrangement)
The outermost shell of the atoms (Ne, Ar, Kr, Xe and Rn) have 8 electrons (octet electron
arrangement)
Atoms of noble gases do not release electrons, accept electrons or share electrons.
Element Electron arrangement of atomHelium / He 2Neon / Ne 2.8Argon / Ar 2.8.8Krypton / Kr 2.8.18.8Xenon / Xe 2.8.18.18.8Radon / Rn 2.8.18.32.18.8
Physical properties
Monoatomic gases
Colourless gas at room temperature
Insoluble in water
Cannot conduct electricity
Poor conductors of heat
Melting point and boiling point increases (going down the group) – atomic size increases and
force of attraction between atoms of each element become stronger
Density of element increases (going down the group)
Chemical properties
Chemically inert / not reactive / non-flammable – do not gain, lose or share electrons with
other elements
Uses
Helium – airships, weather balloons, cool down metals
Neon – advertising light bulb
Argon – welding, filled light bulbs
Krypton – used in laser, filled photographic flash lamps
Radon – treat cancer
SPM Chemistry Form 4 Notes – Periodic Table of Elements (Part 3)
Alkali metal atom arrangement
Group 1 elements
Group 1 elements are known as alkali metals
Atomic radius (atomic size) – increases (going down the group)
The outermost shell of the atoms (Li, Na, K, Rb, Cs and Fr) have 1 valence electron
Good reducing agents
Very reactive – increases (going down the group)
Very electropositive – increases (going down the group)Element Electron arrangement of atomLithium / Li 2.1Sodium / Na 2.8.1Potassium / K 2.8.8.1Rubidium / Rb 2.8.18.8.1Caesium / Cs 2.8.18.18.8.1Francium / Fr 2.8.18.32.18.8.1
Physical properties
Grey solids with shiny silvery surfaces when freshly cut
Soft solids at room temperature
Good conductors of electricity
Good conductors of heat
Low melting point and boiling point (compared to heavy metal)
Melting point and boiling point decreases (going down the group) – atomic size increases
and number of shells occupied with electrons increases / metallic bonding between atoms
becomes weaker & less heat energy is required to overcome the weaker metallic bonding.
Low density (Li, Na and K float on the surface water / Rb, Cs and Fr sink in the water)
Density of element increases (going down the group)
Chemical properties
Chemically very reactive and react rapidly with oxygen and water vapour in the air (must be
kept in paraffin oil)
Reactivity increases (down the group) – how easily it can lose one (single) its valence
electron to achieve stable (octet or duplet) electron arrangement
React vigorously with cold water – produce alkaline metal hydroxide solutions and hydrogen
gas
React with oxygen – produce white solid metal oxides and metal oxides can dissolve in water
to form alkaline metal hydroxide solutions
React with halogens – produce white solid metal halides
Safety precautions
Cannot hold with bare hands
Wear safety goggles and gloves
No flammable substance nearby
Avoid the fire
SPM Chemistry Form 4 Notes – Periodic Table of Elements (Part 4)
by BERRYBERRYTEACHER on 10/03/2011
in BERRY REFERENCE (NOTES)
Molecules of Halogen
Group 17 elements
Group 17 elements are known as halogens
Exist as diatomic molecules (F2, Cl2, Br2, I2 and At2)
Non-metals
Atomic radius (atomic size) – increases (going down the group)
The outermost shell of the atoms (F, Cl, Br, I and At) have 7 valence electrons
Good oxidising agents
Very reactive – decreases (going down the group)
Very electronegative – decreases (going down the group)
Element Electron arrangement of atomFluorine / F 2.7Chlorine / Cl 2.8.7Bromine / Br 2.8.18.7Iodine / I 2.8.18.18.7Astatine / At 2.8.18.32.18.7
Physical properties
Non-metals
Insulators of electricity
Poor conductors of heat
Low melting point and boiling point
Melting point and boiling point increases (going down the group) – molecular size
increases / forces of attraction between molecules become stronger & more heat energy is
required to overcome the stronger forces of attraction (Van der Waals’ forces of attraction
between molecules).
Colour: F2 (pale yellow gas), Cl2 (greenish-yellow gas), Br2 (reddish-brown liquid),
I2 (purplish-black solid) and At2 (black solid – rarest naturally occurring element and
extremely radioactive)
Low density
Density of element increases (going down the group) – increase in atomic mass
Chemical properties
Chemically reactive
Reactivity decreases (down the group) – how easily it can gain one (single) more valence
electron to achieve stable (octet) electron arrangement
React with water – produce two acids
React with hot iron – produce brown solids iron(III) halides
React with sodium hydroxide NaOH solution – produce water and two types of sodium salts
(sodium halide and sodium halite(I))
Safety precautions
Poisonous gas
Wear safety goggles and gloves
Handle in the fume cupboard
SPM Chemistry Form 4 Notes – Periodic Table of Elements (Part 5)
Elements: Zinc Copper Lead Magnesium
Elements in a period
The Periodic Table – 7 periods (Period 1 to Period 7)
Proton number increases by one (across a period – from left to right)
Number of valence electrons of each element increases (across a period – from
left to right)
Across Period 3
Atomic radius / atomic size decreases – increasing number of electrons /
attraction by nucleus on the valence electrons becomes stronger (pulled closer
to the nucleus)
Proton number increases – positive charge of the nucleus increases
Electronegativity (strength to attract electrons towards its nucleus) increases –
proton number increases / positive charge of the nucleus increases
Change from solid to gas
Left – solid metals
Right – non-metals gases
Electropositive / metallic properties decreases
Na, Mg, Al (metals): good conductor / Si (semi-metal): weak conductor of
electricity / P, S, Cl (non-metals): cannot conduct electricity
Na, Mg (metals): form oxides with basic properties
Al (metal): form oxides with both basic and acidic properties = amphoteric
oxides
Si (semi-metal): forms oxides with acidic properties
P, S, Cl (non-metals): forms oxides with acidic properties
Uses of semi-metals (metalloids)
Semiconductor (flow in one direction)
Microchip
SPM Chemistry Form 4 Notes – Periodic Table of Elements (Part 6 – Final)
Transition elements
Elements from Group 3 to Group 12
Metals
Atomic radius (atomic size) approximately the same
Solids with shiny surfaces
Very hard (compared to Group 1 and Group 2 metals)
High density
Ductile (ability to stretched into wires without breaking)
Malleable (ability to be bent into new shape)
High tensile strength (ability to stay in their shape without breaking)
High melting and boiling points
High density
Good conductors of electricity
Good conductors of heat
Electronegativity is low but increases (across the series)3 4 5 6 7 8 9 10 11 12Sc Ti V Cr Mn Fe Co Ni Cu ZnY Zr Nb Mo Tc Ru Rh Pd Ag CdLa Hf Ta W Re Os Ir Pt Au HgAc Rf Db Sg Bh Hs Mt Ds Rg Uub
Colourful Complex of Transition Elements
Special characteristics
Form coloured ions (Cu2+: blue / Fe2+: pale green / Fe3+: yellow)
Form coloured compound (cobalt chloride crystal: pink)
Different oxidation numbers in their compound
Useful catalysts (nickel – hydrogenation of vegetable oil, copper(II)
sulphate – reaction of zinc with dilute sulphuric acid to liberate hydrogen
gas, manganese(IV) oxide – decomposition of hydrogen peroxide to liberate
oxygen gas, iron – Haber process,vanadium(V) oxide – Contact
process, platinum – Ostwald process)
Form complex ions (bigger-sized polyatomic ion) (Hexacyanoferrate(III) ion /
[Fe(CN)6]3- )
Uses
Iron – used as steel
Chromium – coating corroded metals, heat-resisting alloys and make stainless
steel
Copper – making cables, pipes and electrical wires
Titanium – metal pipes and tanks, wings of supersonic aircraft