Counting Atoms and Elements

Front

What is the definition of an atom?

Back

An atom is the smallest unit of matter that retains the properties of an element.

Front

What is the definition of an element?

Back

An element is a pure substance that cannot be broken down into simpler substances by chemical means and is made up of atoms with the same number of protons.

Front

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

Back

To determine the total number of atoms in a chemical formula, add up the subscripts of all the elements present in the formula.

Front

What does a subscript in a chemical formula indicate?

Back

A subscript in a chemical formula indicates the number of atoms of the element that are present in the molecule.

Front

How many total atoms are in the compound H2SO4?

Back

There are 7 total atoms in H2SO4 (2 Hydrogen, 1 Sulfur, and 4 Oxygen).

Front

What is the significance of parentheses in chemical formulas?

Back

Parentheses in chemical formulas indicate that the atoms inside the parentheses are grouped together and the subscript outside applies to all atoms within the parentheses.

Front

How many oxygen atoms are in Al(OH)3?

Back

There are 3 oxygen atoms in Al(OH)3.

Front

What is the formula for calculating the number of different elements in a compound?

Back

Count the number of unique element symbols in the chemical formula.

Front

How many different elements are present in the compound H2COCH2?

Back

There are 3 different elements present in H2COCH2 (Hydrogen, Carbon, and Oxygen).

Front

What is the role of coefficients in a chemical formula?

Back

Coefficients indicate the number of molecules or moles of a compound present in a reaction.