Period 3

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Total cards: 24•Content version: v4•Public deck•Updated: 8/1/2026

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Front (Question)

In period 3, which metal elements react with cold water?

Back (Answer)

Sodium Magnesium

Front (Question)

Describe the reaction between sodium and cold water.

Back (Answer)

Sodium fizzes around on the surface. Strong alkaline solution (pH 13-14) is formed of sodium hydroxide.

Front (Question)

Equation for the reaction between sodium and cold water.

Back (Answer)

2Na (s) + 2H2O (l) -> 2NaOH (aq) + H2 (g)

Front (Question)

Describe the reaction between magnesium and cold water.

Back (Answer)

Reacts slowly with cold water but faster with steam. Solution formed is less alkaline (pH 10) than sodium because magnesium hydroxide is sparingly soluble.

Front (Question)

Equation for the reaction between magnesium and cold water?

Back (Answer)

Mg (s) + 2H2O (l) -> Mg(OH)2 (aq) + H2 (g)

Front (Question)

Equation for the reaction between magnesium and steam?

Back (Answer)

Mg (s) + H2O (g) -> MgO (s) + H2 (g)

Front (Question)

What is the reactivity like for period 3 elements?

Back (Answer)

All reactive except argon

Front (Question)

How are the period 3 oxides formed?

Back (Answer)

By reacting with oxygen in an exothermic reaction.

Front (Question)

Describe sodium reacting with oxygen.

Back (Answer)

Yellow flame. White solid formed.

#10

Front (Question)

Equation for sodium reacting with oxygen?

Back (Answer)

2Na (s) + 1/2O2 (g) -> Na2O (s)

#11

Front (Question)

Describe magnesium reacting with oxygen.

Back (Answer)

A strip of magnesium ribbon burns in air with a bright white flame. White powder of MgO produced. White solid smoke.

#12

Front (Question)

Equation for magnesium reacting with oxygen.

Back (Answer)

2Mg (s) + O2 (g) -> 2MgO (s)

#13

Front (Question)

Describe aluminium reacting with oxygen.

Back (Answer)

Aluminium powder burns in a bright white flame. White solid smoke.

#14

Front (Question)

Equation for aluminium reacting with oxygen.

Back (Answer)

4Al (s) + 3O2 (g) -> 2Al2O3 (s)

#15

Front (Question)

Describe the reaction between silicon and oxygen.

Back (Answer)

Bright white flame. White smoke.

#16

Front (Question)

Equation for silicon reacting with oxygen.

Back (Answer)

Si (s) + O2 (g) -> SiO2 (s)

#17

Front (Question)

Describe the reaction between phosphorus and oxygen.

Back (Answer)

Bright white flame. White smoke.

#18

Front (Question)

Equation for phosphorus reacting with oxygen?

Back (Answer)

4P (s) + 5O2 -> P4O10

#19

Front (Question)

What happens is phosphorus burns in limited oxygen?

Back (Answer)

P2O3 is also formed. Phosphorus trioxide.

#20

Front (Question)

Describe the reaction between sulfur and oxygen.

Back (Answer)

Burns with a blue flame. Acidic choking gas SO2 formed.

#21

Front (Question)

Equation for the reaction between sulfur and oxygen?

Back (Answer)

S (s) + O2 (g) -> SO2 (g)

#22

Front (Question)

Describe the structure of sodium, magnesium and aluminium oxides.

Back (Answer)

Giant ionic lattices High melting points. The strong electrostatic forces of attraction between oppositely charged ions mean they have high melting points. They are ionic because of the large electronegativity difference between metal and oxygen.

#23

Front (Question)

Describe the bonding in aluminium oxide.

Back (Answer)

Ionic Some covalent character. This is because aluminium forms a very small ion with a large positive charge. Thus it can approach closely to the O^2- and distort its electron cloud.

#24

Front (Question)

The bigger the difference in _____________, the greater the ionic character of the bond?

Back (Answer)

Electronegativity