Chemistry -- 8th Grade Science Review

Front

Where are electrons of an atom found?

Back

Electrons are found in the electron cloud surrounding the nucleus of an atom.

Front

What is an example of a substance that is not a chemical compound?

Back

O2 (oxygen gas) is not a chemical compound; it is a diatomic molecule.

Front

What type of bond involves unequal sharing of electrons?

Back

A polar covalent bond involves unequal sharing of electrons.

Front

What happens to atoms during a chemical reaction?

Back

In a chemical reaction, the atoms of the reactants rearrange and re-bond to form the products.

Front

Which observation about burning paper does not indicate a chemical reaction?

Back

The observation that the paper became smaller does not provide evidence of a chemical reaction.

Front

What is a chemical compound?

Back

A chemical compound is a substance formed when two or more elements are chemically bonded together.

Front

What is the difference between an element and a compound?

Back

An element is a pure substance that cannot be broken down into simpler substances, while a compound is made up of two or more elements chemically combined.

Front

What is a chemical reaction?

Back

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.

Front

What is the role of the electron cloud in an atom?

Back

The electron cloud represents the regions around the nucleus where electrons are likely to be found.

Front

What is a diatomic molecule?

Back

A diatomic molecule is a molecule composed of only two atoms, which can be of the same or different chemical elements.