Properties of Alkali Metals Quiz

What is a common physical property of Group 1 metals?

• High density

• Low melting points

• Brittle structure

• Non-metallic appearance

Answer explanation

Group 1 metals, also known as alkali metals, are characterized by low melting points compared to other metals. This property makes them distinct, as they tend to be soft and can be easily cut, unlike the other options listed.

Why are alkali metals stored under oil?

• To prevent corrosion

• To enhance their density

• To prevent reactions with air and water

• To keep them shiny

Answer explanation

Alkali metals are highly reactive, especially with air and water. Storing them under oil prevents these reactions, ensuring their stability and safety.

Which property of alkali metals increases down Group 1?

• Melting point

• Density

• Hardness

• Boiling point

Answer explanation

Density is the property of alkali metals that increases down Group 1. As you move down the group, the atomic mass increases more significantly than the volume, leading to higher density.

What is the trend in reactivity of alkali metals down the group?

• Reactivity decreases

• Reactivity remains constant

• Reactivity increases

• Reactivity fluctuates

Answer explanation

The reactivity of alkali metals increases down the group due to the increasing atomic size and decreasing ionization energy, making it easier for these metals to lose their outermost electron.

Which of the following reactions is typical of Group 1 metals?

• React with water to form alkali and hydrogen gas

• React with acids to form basic oxides

• React with non-metals to form covalent compounds

• React with bases to form salts

Answer explanation

Group 1 metals, such as sodium and potassium, react vigorously with water to produce an alkali (like sodium hydroxide) and hydrogen gas. This reaction is characteristic of these metals, distinguishing them from others.

What gas is produced when sodium reacts with water?

• Oxygen

• Hydrogen

• Chlorine

• Carbon dioxide

Answer explanation

When sodium reacts with water, it produces sodium hydroxide and hydrogen gas. The reaction is vigorous and releases hydrogen, which is why the correct answer is Hydrogen.

Why does reactivity increase down Group 1?

• Atomic size decreases

• Electrostatic forces between the nucleus and valence electrons weaken

• Melting point decreases

• Density decreases

Answer explanation

Reactivity increases down Group 1 because the electrostatic forces between the nucleus and valence electrons weaken. This makes it easier for the outer electron to be lost, enhancing reactivity.

What is the electronic configuration of potassium (K)?

• 2.1

• 2.8.1

• 2.8.8.1

• 2.8.18.1

Answer explanation

The electronic configuration of potassium (K) is 2.8.1, indicating 2 electrons in the first shell, 8 in the second, and 1 in the third. The correct answer is 2.8.1, not 2.8.8.1, which is incorrect.

What product is formed when sodium reacts with chlorine gas?

• Sodium oxide

• Sodium hydroxide

• Sodium chloride

• Sodium carbonate

Answer explanation

When sodium reacts with chlorine gas, they combine to form sodium chloride (NaCl), a common table salt. The other options, such as sodium oxide and sodium hydroxide, involve different reactions.

What type of compounds do alkali metals form with non-metals?

• Covalent compounds

• Ionic compounds

• Molecular compounds

• Amphoteric compounds

Answer explanation

Alkali metals, such as sodium and potassium, readily lose one electron to form positive ions. When they react with non-metals, they form ionic compounds, characterized by the transfer of electrons and the formation of ionic bonds.