Periodic table

Question 1

Who is given the most credit for arranging the periodic table?

Answer 1

Dimitri Mendeleev. At the time there were only 63 known elements so he arranged them in groups of similar chemical properties, increasing atomic number, and left gaps for the undiscovered elements.

Question 2

What are the properties of metals?

Answer 2

• high melting and boiling point
• conductor of heat and electricity
• shiny
• strong
• form cations
• ductile and malleable
• opaque

Question 3

What are the properties of non metals?

Answer 3

• Low melting and boiling point
• poor conductors of heat and electricity
• brittle when solid
• dull colour
• weak
• form anions
• transparent in a thin sheet

Question 4

What happens as you go down a Group?

Answer 4

The number of occupied shells increases so the atomic radii increases due to valence electrons being further away from the nucleus.

Question 5

What happens as you go across the periodic table?

Answer 5

The core charge increases due to a higher number of protons in the nucleus attracting the outer shell electrons closer to the nucleus.

Question 6

Trends in ionisation energy?

Answer 6

Across period: increases due to stronger core charge pulling electrons closer to nuclei
Down group: decreases due to increase in sheliding effect. Electrons are further away and core charge is weak.

Question 7

What is ionisation energy?

Answer 7

The energy required to removed a highest energy electron of an atom. Reflects how tightly electron is held to the nucleus. Only between one atom.

Question 8

Trends in electronegativity?

Answer 8

Across period: increases due to stronger core charge and therefore greater attraction of nucleus that can attract electrons.
Down group: decrease due to nuclear charge being weaker and electrons being further away.

Question 9

What is elecrtonegativity?

Answer 9

The ability of an atom to attract electrons closer to its nucleus in a molecule.

Question 10

What is the metallic character of an element?

Answer 10

Refers to how easily outer shell electrons are lost. This is due to a weaker core charge and increasing sheliding effect.

Question 11

Chemical relativity trends of metals?

Answer 11

Measure of how readily an element will react with another element. Increases down a group because valence electrons are easily lost. Decreases across people because core charge keeps electrons pulled tightly to nucleus.

Question 12

Chemical reactivity of nonmetals?

Answer 12

How readily a non metal will accept electrons. Decreased down group because weaker core charge. Increases across period because stronger core charge.

Question 13

Will anions have a smaller or larger atomic radii than original atom?

Answer 13

Smaller radius due to there being more protons than electrons and decrease in sheliding effect.

Question 14

Will cations have a smaller or larger atomic radii than neutral atoms?

Answer 14

Larger radius due to there being more electrons than protons.

Question 15

What is the octet rule?

Answer 15

When atoms react to achieve a stable outer shell configuration of 8 electrons.

Question 16

Compare alkali metals with alkaline earth metals?

Answer 16

Alkali metals form a +1 iron and are extremly reactive due to a low core charge. Whereas alkaline earth metals are less reactive and form a +2 ion.

Question 17

What are the halogens?

Answer 17

Gain electrons instead of losing them. Very reactive because of their strong core charge. Their reactivity decreases down the group.

Question 18

Difference between bohrs model and the quantum mechanics model?

Answer 18

Shells in Bohr’s model were fixed paths occupied by electrons, whereas in the quantum
mechanical model they are regions of space where
electrons are likely to be found.
The current model specifies that there are subshells and orbitals within shells; these are not
part of the Bohr model.