Physics Exam July 2026

What is the Periodic Table?

A chart that organises the chemical elements

it helps chemists predict how elements will react in chemical reactions

and elements are arranged according to their properties

Who devised the first useful Periodic Table and when?

Dmitri Mendeleev

How did Mendeleev arrange the elements?

In order of increasing atomic mass

he called the vertical columns groups and the horizontal rows periods

What did Mendeleev do where no known element fitted?

He left gaps in his table and predicted the properties of several missing elements

What happened to Mendeleev's prediction of eka-silicon?

The element germanium was later discovered and its properties matched Mendeleev's predictions closely

How is the modern Periodic Table arranged?

In order of increasing proton number (atomic number)

it contains 118 known elements

Who showed that elements are better arranged by proton number than atomic mass?

Ernest Rutherford and Henry Moseley

What are periods?

The horizontal rows of the Periodic Table

What are groups?

The vertical columns of the Periodic Table

in traditional notation numbered Group I to Group VIII

What are metalloids?

Elements on the zig-zag line dividing metals and non-metals

they behave in some ways like metals and in other ways like non-metals

What is the trend across a period from left to right?

A gradual change from metal to non-metal

the number of electrons in the outer shell increases

structure changes from giant metallic

to giant covalent

Which elements are in Group I?

Lithium

General physical properties of Group I metals

Very reactive metals stored under oil

good conductors of heat and electricity

soft metals (lithium hardest

potassium softest)

low densities

shiny surfaces when freshly cut

low melting points

Why are Group I metals stored under oil?

So they do not touch air or water

Group I metals and oxygen

Burn in oxygen or air with characteristic flame colours to form white solid metal oxides

Group I metal oxides and water

React with water to form alkaline solutions of the metal hydroxide

Group I metals and water

React vigorously to form an alkaline solution of the metal hydroxide and hydrogen gas

Order of reactivity with water for lithium

sodium and potassium

Group I metals and halogens

React vigorously with halogens such as chlorine to form white metal halide salts

Trend down Group I

Reactivity increases down Group I

density increases up Group I

francium is predicted to be the most reactive Group I metal

Homework prediction: how does caesium compare to sodium?

Caesium is more dense than sodium

it will also be softer and more reactive

it will have a lower boiling point and melting point than sodium

Which elements are in Group II?

Beryllium

General physical properties of Group II metals

Harder than Group I metals

silvery-grey when pure and clean

tarnish quickly in air

good conductors of heat and electricity

Group II metals and oxygen

Burn in oxygen or air with characteristic flame colours to form solid white metal oxides

Group II metals and water

React with water

Trend down Group II

Reactivity increases down Group II

Which elements are in Group VII

the halogens?

Appearance of chlorine

bromine and iodine at room temperature

bromine is a red-brown liquid

iodine is a grey-black solid

Physical form of halogen elements

They exist as diatomic molecules

Trend in halogen state and melting/boiling point down the group

A gradual change from gas (chlorine)

melting and boiling point increase down the group

Halogens and hydrogen

React with hydrogen to produce hydrogen halides

Halogens and metals

React with metals to form ionic metal halides

Order of reactivity of chlorine

bromine and iodine with iron

Trend in halogen reactivity towards iron down the group

Elements in Group VII become more reactive with iron as you move up the group

Why does iodine have a higher boiling point than chlorine?

Iodine is a solid at room temperature so it requires more energy to break the forces between its molecules than bromine

chlorine is a gas so its intermolecular forces are far weaker

giving it the lowest boiling point of the three

Use of fluorine

Used

Use of chlorine

Used to make PVC plastic and household bleaches

Use of bromine

Used to make disinfectants

Use of iodine

Used in medicines and disinfectants

Which elements are in Group VIII

Group 0?

General properties of the noble gases

Colourless gases

monatomic

existing as single atoms rather than molecules

very unreactive

or chemically inert

Why are noble gases so unreactive?

Their atoms have stable electron configurations that are very difficult to change

Electron configuration of helium

2

Electron configuration of neon

2

Electron configuration of argon

2

Use of argon

Used in filament lamps

Use of neon

Used in advertising signs and in some types of lasers

Examples of transition elements

Copper

Where are transition elements found in the Periodic Table?

In the central block

General properties of transition elements

Less reactive than Groups I and II metals

harder and stronger

much higher densities

usually high melting points

the main exception being mercury

good conductors of heat and electricity

Coloured compounds of transition metals

Copper sulphate is turquoise blue

iron oxide is orange

chromium chloride is green

cobalt chloride is purple

Transition metals as catalysts

Many transition metals and their compounds are useful catalysts

Why don't transition metals corrode quickly?

They react more slowly with oxygen and/or water than many other metals

Diatomic elements that exist as molecules when uncombined

Nitrogen (N2)

What would you observe as calcium reacts with water?

Calcium reacts vigorously with cold water

the boiling tube becomes very hot

showing the reaction is exothermic

bubbles of hydrogen gas are given off and a white precipitate forms

together with an alkaline milky solution of calcium hydroxide

Word equation for calcium and water

Calcium + water → calcium hydroxide + hydrogen

How would magnesium's reaction with water differ from calcium's?

Magnesium will not be as reactive in water as calcium

in reality magnesium reacts very slightly

with a few bubbles of hydrogen forming on the surface before the reaction stops quickly

Three differences between Newlands' periodic table and the modern periodic table

Modern table is arranged by atomic number

the modern table has metals on the left and non-metals on the right

but Newlands placed the non-metals F and Cl in Group I

Newlands' table was missing many elements and had no noble gases

Why was Newlands' table different from the modern one?

Newlands arranged elements in order of relative atomic mass

What is wrong with Mendeleev's arrangement of tellurium and iodine by atomic mass?

Iodine's relative atomic mass is less than tellurium's

Why is this not a problem in the modern periodic table?

Iodine has a higher atomic number than tellurium

Predicted properties of rubidium compared to potassium

Lower melting and boiling point than potassium

more reactive than potassium