Periodic Table

Question 1

Define periodicity

Answer 1

The trend of physical and chemical properties going across a period and down a group

Question 2

Define a group and period

Answer 2

Group: vertical column in the periodic table - elements have same number of valence electrons
Period: horizontal row in the periodic table - elements have same number of occupied electron shells

Question 3

What are the characteristics of group 1? And why

Answer 3

• Alkali metals
• Most reactive metalas
• low m.p. and b.p. (Relative to metals): weak metallic bonding due to low charge density
• soft due to weak metallic bonding
• low density

Question 4

What are the trends going down group 1?

Answer 4

• Reactivity of metals increases because there are more occupied electron shells, thus valence electrons are higher in energy and are less tightly held and more easily lost
• m.p. and b.p. decreases because charge density decreases, so metallic bonding is weaker
• density increases

Question 5

What are some details about the periodic table?

Answer 5

• more metals than non-metals
• elements change from metallic to non-metallic across the period
• arranged according to proton numbers

Question 6

What is the trend going down for group 17?

Answer 6

Reactivity decreases because the smaller the atom the easier it is to accept, and the harder it is the break the bond

Question 7

What needs to be considered when talking about radii?

Answer 7

• number of occupied electron shells
• number of protons (only if no. of electron shells are the same)

Question 8

What is nuclear charge, shielding effect and effective nuclear charge?

Answer 8

Nuclear charge: attractive force by proton number
Shielding effect: repulsive force by inner electrons
Effective nuclear charge: