Unit 2 part 5 - Periodicity in reactivity

Question 1

How are the chemical properties of an element determined?

Answer 1

By the electron configuration of its atoms

Question 2

Why do elements of the same group are similar chemical properties?

Answer 2

B/c they have the same number of valence electrons in outer energy level

Question 3

Group 1 - alkali metals features?

Answer 3

1. Too reactive to be found in nature
2. Soft and shiny
3. Stored in oil to prevent reaction with air and water
4. Lowest ionization energy (lose outer electrons)

Question 4

Least reactive elements?

Answer 4

The noble gasses
- Group 18

Question 5

What do elements in different groups do to achieve the same electron config of their nearest noble gas?

Answer 5

Lose or gain electrons

Question 6

Physical properties of alkali metals?

Answer 6

1. Good electricity and heat conductors
2. Low densities
3. Shiny grey surfaces when freshly cut with knives

Question 7

Chemical properties of alkali metals?

Answer 7

1. Very reactive metals
2. Form ionic-compounds w/ non-metals

Question 8

Why does reactivity increase down group 1?

Answer 8

B/c the elements with the higher atomic numbers have the lowest ionization energies

Question 9

Alkali metals react with water to produce what?

Answer 9

Hydrogen and metal hydroxide

Question 10

What happens to Li when dropped into a beaker w/distilled water?

Answer 10

Floats and reacts slowly
- Releases hydrogen but keeps its shape

Question 11

What happens to Na when dropped in beaker w/distilled water?

Answer 11

Reacts with vigorous release of hydrogen
- Heat produced is sufficient to melt unreacted metal and forms a small ball that floats

Question 12

What happens to K when its dropped in a beaker w/distilled water?

Answer 12

Reacts very vigorous to produce heat to ignite the hydrogen produced
- Produces lilac flame and moves excitedly to surface of water

Question 13

Ex. of group 1 reacting with water

Answer 13

2K(s) + 2H2O(l) –> 2KOH(aq) + H2(g)

Question 14

Features of group 18 - The noble gasses

Answer 14

1. Full sublevels
2. Unreactive
3. Colourless gasses
4. Monotomic ( exists as single atom)
5. Extremely high ionization energy

Question 15

What do group 17 elements - halogens usually exist as?

Answer 15

Diatomic molecules
- X2

Question 16

Physical properties of halogens?

Answer 16

1. Coloured
2. Show a gradual change from gasses (f2 and Cl2) to liquids (Br2) to solids (I2 and At2)

Question 17

Chemical properties of halogens?

Answer 17

1. Very reactive non-metals
2. Form ionic compounds with metals
3. Form covalent compounds with non-metals

Question 18

Why does reactivity decrease down group 17?

Answer 18

B/c atomic radius increases and attraction for outer electrons decreases

Question 19

When halogens and alkali metals react what do they form?

Answer 19

Halides

Question 20

Ex. of group 1 and 17 reactions

Answer 20

2NaCl + F2 (most reactive) –> 2NaF + Cl2

Question 21

What does a loss of electrons indicate in reactions?

Answer 21

Oxidization

Question 22

What does a gain of electrons indicate In reactions?

Answer 22

Reduced

Question 23

Bonding of period 3 elements with oxygen?

Answer 23

1. Giant ionic structures
2. Have an endlessly repeating latice (pattern)

Question 24

Why do structures of high melting and boiling point?

Answer 24

B/c of strong attractions between particles

Question 25

Why do oxides become more ionic down a group?

Answer 25

B/c of difference in Electronegativity

Question 26

What are oxidation states?

Answer 26

The number assigned to show the number of electrons transferred when forming a bond