Alkali Metals and Chemical Reactions

Question 1

Define reactivity in chemistry.

Answer 1

How readily a substance undergoes chemical reaction.

Question 2

In alkali metals, the as atomic number increases which properties also increase?

Answer 2

Reactivity, atomic radius, ionic radius and density

Question 3

In alkali metals, the as atomic number increases which properties decrease?

Answer 3

Melting point, ionization energy, electronegativity and boiling point.

Question 4

Define electronegativity

Answer 4

χ or electronegativity is the tendency for an atom to attract atoms towards themselves.

Question 5

In the following reaction relating to alkali metals, what does it create: 2Na + 2(H2O)

Answer 5

2(NaOH) + H2

Question 6

In the following reaction relating to alkali metals, what does it create:
2Li + 2(H2O)

Answer 6

2(LiOH) + H2

Question 7

In the following reaction relating to alkali metals, what does it create: Na (when it gives away an electron)

Answer 7

Na^+ + e^-, Reduction reduction potential: 2.71 volts

Question 8

What is reduction potential?

Answer 8

A tendency for something to acquire or lose electrons.

Question 9

In the following reaction relating to alkali metals, what does it create:
Li (When it loses an electron)

Answer 9

Li^+ + e^- Reduction potential: 3.05 volts

Question 10

In the following reaction relating to alkali metals, what does it create:
2Na + Cl2

Answer 10

2(NaCl)

Question 11

In the following reaction relating to alkali metals, what does it create: 4Li + O2

Answer 11

2(Li2O)

Question 12

In the following reaction relating to alkali metals, what does it create:
4Na + (Limited) O2

Answer 12

2(Na2O) (Sodium Oxide)

Question 13

In the following reaction relating to alkali metals, what does it create: 2Na + (Excess) O2

Answer 13

Na2O2 (Sodium Peroxide)

Question 14

In the following reaction relating to alkali metals, what does it create: K + O2

Answer 14

KO2 (Potassium Superoxide)

Question 15

What does oxidation state mean?

Answer 15

Hypothetical charge of an ion atom if all of its bonds to other atoms were ionic.

Question 16

What does the prefix “per” mean in chemistry?

Answer 16

The very highest oxidation state (hydrogen peroxide means hydrogen + oxygen at its highest oxidation state)

Question 17

What does the prefix “super” mean in chemistry?

Answer 17

Indicates that a chemical compound contains a specific element in higher proportion than usual.

Question 18

Why are alkali metals with higher atomic numbers more reactive?

Answer 18

For reference let’s use lithium and cesium:
Lithium only has two shells meaning the pull on the electron is stronger, thus making it harder for it to be given away. Cesium has 6 shells, meaning the nucleus pull is a lot weaker, allowing it to be given up easier.

A second reason is that the melting point of lithium is 180c while for cesium is only around 29c. Molten versions of atoms are much more reactive then their solid counterparts.