Elements And Compounds

Question 1

Define element.

Answer 1

A substance that cannot be broken down into simpler substances by chemical means.

Question 2

What is a compound?

Answer 2

A substance formed when two or more elements chemically bond together.

Question 3

True or false: Water is a compound.

Answer 3

TRUE

Water is made of hydrogen and oxygen (H2O).

Question 4

Fill in the blank: An atom consists of protons, neutrons, and _______.

Answer 4

Electrons

Question 5

What is the smallest unit of an element?

Answer 5

An atom.

Question 6

Define molecule.

Answer 6

A group of two or more atoms bonded together, representing the smallest fundamental unit of a chemical compound.

Question 7

True or false: Sodium chloride is an element.

Answer 7

FALSE

Sodium chloride (table salt) is a compound made from sodium and chlorine.

Question 8

What is the chemical formula for carbon dioxide?

Answer 8

CO2

Question 9

Fill in the blank: The periodic table organizes elements by their _______.

Answer 9

Atomic number

Question 10

Define ionic bond.

Answer 10

A chemical bond formed through the transfer of electrons from one atom to another.

Question 11

What type of bond involves sharing electrons?

Answer 11

Covalent bond.

Question 12

True or false: Helium is a noble gas.

Answer 12

TRUE

Noble gases are inert and do not readily react with other elements.

Question 13

What is the main characteristic of metals?

Answer 13

They are good conductors of heat and electricity.

Question 14

Fill in the blank: Acids are substances that release _______ ions in solution.

Answer 14

Hydrogen

Question 15

Define base.

Answer 15

A substance that can accept hydrogen ions or donate electron pairs in reactions.

Question 16

What is a mixture?

Answer 16

A combination of two or more substances that retain their individual properties.

Question 17

True or false: Oxygen is essential for combustion.

Answer 17

TRUE

Oxygen supports the burning of fuels in combustion reactions.

Question 18

What is the atomic number of carbon?

Answer 18

6

Question 19

Fill in the blank: Hydrogen is the most abundant _______ in the universe.

Answer 19

Element

Question 20

Define alloy.

Answer 20

A mixture of two or more metals, or a metal and another element.

Question 21

What is the main component of air?

Answer 21

Nitrogen (approximately 78%).

Question 22

True or false: Chlorine is a metal.

Answer 22

FALSE

Chlorine is a non-metal and is a gas at room temperature.

Question 23

What is a reactant?

Answer 23

A substance that undergoes a chemical change in a reaction.

Question 24

Fill in the blank: Synthesis reactions involve combining two or more _______.

Answer 24

Reactants

Question 25

Define **oxidation**.

Answer 25

A chemical reaction that involves the loss of electrons.

Question 26

What is the **pH scale** used for?

Answer 26

To measure the acidity or alkalinity of a solution.

Question 27

True or false: **Noble gases** are highly reactive.

Answer 27

FALSE ## Footnote Noble gases are known for their lack of reactivity due to a full valence shell.

Question 28

What is the **main difference** between elements and compounds?

Answer 28

Elements consist of one type of atom, while compounds consist of two or more different atoms.

Question 29

Fill in the blank: **Organic compounds** primarily contain _______.

Answer 29

Carbon

Question 30

Define **hydrocarbon**.

Answer 30

An organic compound consisting entirely of hydrogen and carbon.

Question 31

What is the **chemical symbol** for gold?

Answer 31

Au

Question 32

True or false: **Iron** is a transition metal.

Answer 32

TRUE ## Footnote Transition metals are found in the d-block of the periodic table.

Question 33

What is a **polyatomic ion**?

Answer 33

An ion composed of two or more atoms bonded together that carries a charge.

Question 34

Fill in the blank: **Nitric acid** is represented by the formula _______.

Answer 34

HNO3

Question 35

Define **solvent**.

Answer 35

A substance that dissolves a solute, resulting in a solution.

Question 36

What is the **main use** of sodium bicarbonate?

Answer 36

It is commonly used as a baking soda.

Question 37

True or false: **Copper** is a good conductor of electricity.

Answer 37

TRUE ## Footnote Copper is widely used in electrical wiring due to its conductivity.

Question 38

What is the **process** of separating a mixture by boiling point called?

Answer 38

Distillation.

Question 39

Fill in the blank: **Ammonia** has the chemical formula _______.

Answer 39

NH3