Physical and Chemical Properties

Question 1

List basic properties of Alkali metals:

Answer 1

• Group consists of the most reactive metals on the periodic table
  
  • Reactivity increases down the group
  • Act as good reducing agents
• Alkali metals and water react violently to form strong bases and hydrogen gas according to the following general reaction:

2M_(s) + 2H₂O_(l) → MOH_(aq) + H_{<strong>2(g)</strong>} (M denotes an alkali metal)

• All alkali metals react directly with hydrogen forming ionic bonds:

2M_(l) + H₂(g) → 2MH_(s)

• Alkali metals and halogens combine to form ionic salts through an extremely exothermic reaction:

M_(s) + X_2(g) –> M₂X_(s) (X denotes a halogen)

• Alkali metals and acid react to produce salts of the metal and the acid which exist as the ionized components, hydrogen is liberated as a gas.

Question 2

What is the flame color of sodium?

Answer 2

Golden yellow

Question 3

What is the flame color of lithium?

Answer 3

Crimson

Question 4

What is the flame color of potassium?

Answer 4

Red/violet

Question 5

What is the flame color of Rubidium?

Answer 5

Blue/violet

Question 6

What is the flame color of Cesium?

Answer 6

Blue/violet

Question 7

List basic properties of Halogens:

Answer 7

Exist in nature as diatomic molecules

• Group consists of the most reactive nonmetals on the periodic table
  
  • Reactivity increases up the group
  • Act as good oxidizing agents
• All halogens react directly with hydrogen, forming covalent bonds
• Halogens and alkali metals combine to form ionic salts through an extremely exothermic reaction:

M_(s) + X_2(g) → M₂X_(s) (M denotes alkali metal)

• Halogens and alkaline earth metals combine to form ionic salts:

**M + X₂ → MX₂ **(M deontes any alkaline earth metal and X represents fluorine, chlorine, bromine, or iodine)

Question 8

Define an alloy:

Answer 8

An alloy is a substance made by melting two or more elements together, at least one of them a metal. An alloy crystallizes upon cooling into a solid solution, mixture, or intermetallic compound.

Question 9

What is combined with copper to make bronze?

Answer 9

Bronze is an alloy of Tin and Copper

Question 10

What is combined with copper to make brass?

Answer 10

Brass is an alloy of Zinc and Copper

Question 11

What is combined with Carbon to make steel?

Answer 11

Steel is an alloy of Iron and Carbon.

Question 12

Define and list the three groups of hydrides:

Answer 12

Hydride: Binary compound formed by hydrogen and other elements of the periodic table

Covalent Hydride: Type of hydride in which a hydrogen atom and one or more non-metals form a compound

Ionic Hydride: Type of hydride in which compounds form between hydrogen and the alkali and alkaline-earth metals of group one and two elements

Metallic Hydride: Type of hydride in which hydrogen bonds with transition metals

Question 13

List basic properties of Ionic Hydrides:

Answer 13

• Hydrogen acts as the hydride ion (H^-)
• Insoluble in solutions
• React vigoursly with water to produce hydrogen gas

2M_(s) + H_2(g) → 2MH_(s)(M denotes any alkali metal)

**_{<span>M</span>(s)} + H_2(g) → MH_2(s) **(M denotes any alkali earth metal)

Question 17

List basic properties of alkaline earth metals:

Answer 17

• Group consists of reactive metals on the periodic table
  
  • Reactivity increases down the group
• Reactions with water show the relative alkalinity of alkaline earth metals:
  
  • **Alkaline earth metal + water → metal hydroxide **(BeO shows acidic properties)
  • More active alkaline earth metals react with water like alkali metals do: Ca²⁺, Sr²⁺, and Ba²⁺ react with water producing H₂ gas
• All alkali earth metals react with hydrogen to create metallic hydrides
• Alkaline earth metals and halogens combine to form ionic salts:

**M + X₂ → MX₂ **(M deontes any alkaline earth metal and X represents fluorine, chlorine, bromine, or iodine)

Question 18

Define Alkalinity:

Answer 18

Quantitative measurement of the ability of an aqueous solution to neutralize an acid