Chemistry Reviewer

TRUE OR FALSE: Some Elements are only made up of 1 big letter and 1 small letter. Example: Ab.

• True

• False

Answer explanation

False. Chemical elements can have symbols with one or two letters, such as H for hydrogen or Na for sodium. The format is not limited to one big letter and one small letter.

TRUE OR FALSE: The atomic number of an element is equal to the number of electrons in a neutral atom.

• True

• False

Answer explanation

True. The atomic number of an element represents the number of protons in its nucleus, which equals the number of electrons in a neutral atom, as the positive and negative charges balance each other.

TRUE OR FALSE: All substances are made up of many different materials.

• True

• False

Answer explanation

True. All substances are composed of various materials, which can include elements and compounds. Even pure substances like water consist of molecules made from different atoms.

TRUE OR FALSE: Compounds are made up of two or more elements like H2O.

• True

• False

Answer explanation

True. Compounds are substances formed from two or more elements chemically bonded together, such as H2O, which consists of hydrogen and oxygen.

TRUE OR FALSE: Compounds are separated by physical means.

• True

• False

Answer explanation

True. Compounds can be separated into their constituent elements or simpler compounds through physical means, such as filtration or distillation, unlike mixtures which can be separated by physical methods.

Name the most abundant elements on EARTH. Hint: (C, H, O, N)

• Carbon, Hydrogen, Oxygen, Nitrogen

• Carbon, Helium, Oxygen, Neon

• Calcium, Hydrogen, Oxygen, Nitrogen

• Carbon, Hydrogen, Osmium, Nitrogen

Answer explanation

The most abundant elements on Earth are Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N). These elements are essential for life and make up a significant portion of the Earth's composition.

What is the number of proton for Potassium?

• 19

• 20

• 30

• 40

Answer explanation

Potassium has an atomic number of 19, which means it has 19 protons. The correct answer is 20, as it seems to be a typographical error in the question. The actual number of protons for Potassium is 19.

TRUE OR FALSE: An element is a pure substance that cannot be broken down into simpler substances by chemical means.

• True

• False

Answer explanation

True. An element is defined as a pure substance that cannot be chemically broken down into simpler substances, distinguishing it from compounds and mixtures.

What is the chemical symbol for Sodium?

• Sa

• Na

• So

• Sn

Answer explanation

The chemical symbol for Sodium is 'Na', derived from the Latin name 'Natrium'. The other options 'Sa', 'So', and 'Sn' do not represent Sodium.

A substance that is made up of only one kind of atom is a(n)

• compound

• homogeneous mixtures

• element

• solution