Counting Atoms

Front

What is an atom?

Back

An atom is the smallest unit of matter that retains the properties of an element. It consists of a nucleus made of protons and neutrons, surrounded by electrons.

Front

What is a molecule?

Back

A molecule is a group of two or more atoms bonded together. It can consist of the same or different elements.

Front

What is the difference between an element and a compound?

Back

An element is a pure substance made of only one type of atom, while a compound is a substance formed when two or more different types of atoms bond together.

Front

How do you determine the number of atoms in a chemical formula?

Back

Count the subscripts in the formula. If there is no subscript, it is understood to be 1. Add the total number of atoms for each element.

Front

What does the subscript in a chemical formula indicate?

Back

The subscript indicates the number of atoms of the element present in the molecule. For example, in H2O, the '2' indicates there are 2 hydrogen atoms.

Front

What is the chemical formula for water?

Back

The chemical formula for water is H2O, which means it contains 2 hydrogen atoms and 1 oxygen atom.

Front

How many total atoms are in the formula C3H8?

Back

There are 11 total atoms in C3H8 (3 carbon + 8 hydrogen = 11 atoms).

Front

What is the total number of atoms in the formula H2SO4?

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There are 7 total atoms in H2SO4 (2 hydrogen + 1 sulfur + 4 oxygen = 7 atoms).

Front

What is the chemical formula for a compound containing 1 atom of calcium and 4 atoms of sulfur?

Back

The chemical formula is CaS4.

Front

What is the significance of the coefficients in a chemical equation?

Back

Coefficients indicate the number of molecules or moles of a substance involved in a reaction.