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.

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What is a coefficient in a chemical equation?

Back

A coefficient is a number placed in front of a chemical formula in a reaction to indicate how many molecules or moles of that substance are involved.

Front

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

Back

To calculate the total number of atoms, add the subscripts of each element in the formula, multiplied by the coefficient if present.

Front

What does a subscript indicate in a chemical formula?

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

Front

How many total atoms are in the formula ClN6Fe2?

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There are 9 total atoms: 1 Cl + 1 N + 6 (from N) + 2 (from Fe) = 9.

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What is the total number of hydrogen atoms in the formula 5Cl2H5?

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There are 25 hydrogen atoms: 5 (from H5) multiplied by 5 (coefficient) = 25.

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How many atoms of Iron are in the formula 2HFe5Cl?

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There are 10 iron atoms: 5 (from Fe5) multiplied by 2 (coefficient) = 10.

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What is the total number of atoms in the formula 2(H2)3?

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There are 12 total atoms: 2 (coefficient) multiplied by 3 (from H2) = 6, and 6 from the parentheses = 12.

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What is the difference between a molecule and a compound?

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A molecule is two or more atoms bonded together, while a compound is a type of molecule that contains at least two different elements.

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What is the significance of balancing a chemical equation?

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Balancing a chemical equation ensures that the law of conservation of mass is followed, meaning the number of atoms of each element is the same on both sides of the equation.