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