Periodicity

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A level Chemistry (Inorganic Chemistry) Flashcards on Periodicity, created by Anushka John on 25/11/2016.
Anushka John
Flashcards by Anushka John, updated more than 1 year ago
Anushka John
Created by Anushka John over 7 years ago
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Question Answer
Elements are classed as s, p or d according to what? The orbital the highest energy electron is in
What happens to atomic radius as you go across (left to right) the period? *atomic radius decreases *increased number of protons in the nucleus, so greater nuclear charge *without much difference in shielding *causes stronger attraction to outer electrons, so they are pulled closer (same in period 2)
What is the general trend for 1st ionisation energy across both period 2 and 3? GENERALLY increases This is due to the increased number of protons, so there is a greater positive nuclear charge attracting the outer electrons, making them harder to remove
What is the first anomaly in the trend of 1st ionisation energy across period 2 and 3? PERIOD 2: small drop between Be and B * the outermost electron in Be is in 2s and in B is in 2p, which is a higher energy level so easier to remove PERIOD 3: small drop between Mg and Al ( same as above, expect replace 2s -> 3s and 2p -> 3p)
What is the second anomaly in 1st ionisation energy across period 2 and 3? PERIOD 2: small drop between nitrogen and oxygen O's outer electron paired with another electron in the same 2p orbital. Mutual repulsion makes it slightly easier to remove PERIOD 3: small drop between phosphorus and sulphur S's outer electron paired with another electron in the same 3p orbital. Mutual repulsion makes it slightly easier to remove
Explain the trend for Na. Mg and Al METALLIC BONDING *Strong intermolecular bond * Gets stronger the more electron there are in the outer shell - as more electrons are released into the sea of delocalised electrons. *lots of energy needed to overcome electrostatic forces of attraction between electrons and ions
Explain why Si has the highest boiling point? MACROMOLECULAR * many strong covalent bonds between the atoms * high energy needed to break covalent bonds
Explain the trend in boiling points for P4(s), S8(s) and Cl2 (g) SIMPLE MOLECULAR *weak van Der Waals ofrces of attraction between the molecules *little energy is needed to overcome them *boiling point for S8 >P4> Cl2 as it has more electrons and so greater van Der Waals between the molecules.
Explain why Ar has the lowest boiling point MONOATOMIC GAS *very weak van Der Waals between the atoms and so very easily overcome
Period 2 has a similar trend in boiling points to Period 3. Describe the bonding in the different Period 2 elements and their relative boiling points. Li and Be - METALLIC (high bp) B and C - MACROMOLECULAR (very high bp) N2 and O2 - SIMPLE MOLECULAR gases (low bp) Ne - MONOATOMIC gas (very low bp)
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