Atoms & Periodic Table

Front

What is an element?

Back

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include gold, oxygen, and hydrogen.

Front

What is a compound?

Back

A compound is a substance formed when two or more elements are chemically bonded together. Examples include water (H2O) and carbon dioxide (CO2).

Front

What is a mixture?

Back

A mixture is a combination of two or more substances that are not chemically bonded. Examples include air and salad.

Front

What is a mole in chemistry?

Back

A mole is a unit of measurement used to express amounts of a chemical substance, defined as exactly 6.022 x 10^23 particles (atoms, molecules, etc.).

Front

Where is most of the mass in an atom concentrated?

Back

Most of the mass in an atom is concentrated in the nucleus, which contains protons and neutrons.

Front

What charge do Group 2 elements have?

Back

Group 2 elements have a charge of +2 when they form ions.

Front

Who was the first person to propose atomic theory?

Back

Democritus was the first person to propose the idea of atomic theory, suggesting that matter is made up of small, indivisible particles called atoms.

Front

What are protons?

Back

Protons are positively charged particles found in the nucleus of an atom. The number of protons determines the element's identity.

Front

What are neutrons?

Back

Neutrons are neutral particles found in the nucleus of an atom. They contribute to the mass of the atom but do not affect its charge.

Front

What are electrons?

Back

Electrons are negatively charged particles that orbit the nucleus of an atom. They are involved in chemical bonding.