Trends across the Period

Multiple Choice

The elements shown are in the same Period, identify the element with the largest atoms.

• A

• B

• C

• D

Multiple Choice

The atoms of 4 elements in the SAME period are shown. Which atom would you predict would be in Group 8/0.

• K

• L

• M

• N

​Trends across the period

Size of the atoms have the same effect on factors as it does down the group.

e.g. Electronegativity is the ability to attract electrons and it increases with decreasing atomic size. Therefore

​-Down the group it decreases (as atoms get larger)

-Therefore across the period Electronegativity increases​ (as atoms get smaller)

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Multiple Choice

Ionisation Energy is the energy required to remove an electron from the valence shell. Given that atomic radius decreases across the period what would you predict to be the trend in ionisation energy across (left to right) the period?

• Stays the same

• Increases

• Decreases

Multiple Choice

Electropositivity is the ability of an atom to lose electrons to form positive ions. Given that atomic radius decreases across the period what would you predict to be the trend in electropositivity across (left to right) the period?

• Stays the same

• Increases

• Decreases

​Trends across the Period

​Factor	​Trend	​Explanation
​Ionisation energy	​Increases	​As atoms get smaller, valence e- get closer to pull of nucleus and are more strongly held in the valence shell. More energy is therefore required to remove e-
​Electropositivity	​Decreases	​As atoms get smaller and valence e- are more strongly attracted to nucleus, it gets harder to lose electrons.

Reactivity of Metals

Multiple Choice

Metals are elements which react by losing electrons to form positive ions. Use the diagram of metal atoms in Period 3 and predict which metal would be more reactive.

• Sodium (Na)

• Magnesium (Mg)

• Aluminium (Al)

Multiple Choice

Given that atomic radius decreases across the period, predict the REACTIVITY of METALS across the period.

• Stays the same

• Increases

• Decreases

Multiple Choice

Explain why Sodium is more reactive than Magnesium and Aluminium.

i. It has the largest atomic radius

ii. It has the highest ionisation energy

iii. Its atoms have only 1 valence electron to lose while the others have more to lose

• iii only

• i and ii only

• i, ii and iii

• i and iii only

Reactivity of Non-Metals

Multiple Choice

Non-Metals are elements which react by gaining electrons to form negative ions. Use the diagram of non-metal atoms in Period 3 and predict which would be more reactive.

• Silicon (Si)

• Phosphorous (P)

• Sulphur (S)

• Chlorine (Cl)

Multiple Choice

Given that atomic radius decreases across the period, predict the REACTIVITY of NON-METALS across the period.

• Stays the same

• Increases

• Decreases

Multiple Choice

Explain why Chlorine is more reactive than the other non-metals shown.

i. It has the smallest atomic radius

ii. It has the highest ionisation energy

iii. Its atoms have to gain 7 valence electrons.

• i only

• i and ii only

• i, ii and iii

• i and iii only