Unit 2 Section 1: Periodicity Flashcards

1
Q

Describe the trend in atomic radius across period 3 of the periodic table.

A

Decrease

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2
Q

Describe the trend in melting points across period 3 of the periodic table.

A

The melting points increase from sodium to silicon, then generally decrease from silicon to argon.

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3
Q

Describe the general trend in first ionisation energy across period 3 of the periodic table.

A

There’s a general increase in firs ionisation energy as you go across period 3.

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4
Q

Explain why the atomic radius of aluminium is larger than the atomic radius of sulfur.

A

Aluminium has 13 protons and sulfur has 16 protons, so the positive charge of the nucleus of sulfur is greater. This means electrons are pulled closer to the nucleus, making the atomic radius of sulfur smaller than the atomic radius of aluminium.

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5
Q

Name a period 3 element with a larger atomic radius than aluminium.

A

Sodium/magnesium

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6
Q

Explain why the first ionisation energy of sulfur is higher than the first ionisation energy of aluminium.

A

Sulfur has more protons than aluminium so its electrons are attracted more strongly towards the nucleus. This means it takes more energy to remove an electron from each atom, so it has a higher first ionisation energy

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7
Q

Explain why the melting pint of phosphorus is lower than silicon.

A

Silicon is macro molecular so has strong covalent bonds linking all its atoms together. Phosphorus is a molecular substance with van der Waals forces between molecules. It takes much less energy to break van der Waals forced than covalent bonds

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8
Q

Name a period 3 element with a lower melting point than phosphorus.

A

Chlorine/argon

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9
Q

Predict the element in period 3 that has the highest second ionisation energy. Give a reason for your answer.

A

Sodium - the electron must be removed from the second shell, which is closer to the nucleus, so there is more attraction

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10
Q

Explain why the ionisation energy of every element is endothermic

A

Energy is needed to overcome the attraction between the negative electron and positive nucleus

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11
Q

State the meaning of the term electronegativity

A

An atom’s ability to attract electrons towards itself in a covalent bond

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12
Q

Suggest why the electronegativity of the elements increases from lithium to fluorine.

A

Nuclear charge increases due to more protons and shielding remains the same because the number of inner electrons stays the same

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