The Chemistry of Life

Atoms and ElementsChapter 6

6. An atom is the smallest

particle of an element that

has the characteristics

of that element.

7. Atoms are the basic building

blocks of all matter.

8. The nucleus is the center of an atom. The nucleus contains protons (+) and neutrons (0).

The electron cloud is the area surrounding the nucleus and it contains electrons (-).

• The atomic number of an element is equal to the number of protons the element has.• Atoms always contain the same

number of protons and electrons• Atomic # = protons = electrons• # neutrons = atomic mass – atomic #

Everything is made of substances called elements.

An element is a substance that can’t be broken down into simpler chemical

substances.

Carbon, hydrogen,

oxygen, and nitrogen are the

four elements that make up

more than 96% of the mass of a

human body.

Each element is identified by a one- or two-letter abbreviation called a symbol.

5. List 5 elements.

• Atoms of the same element that have different numbers of neutrons are called isotopes.

• Ex: Carbon normally has 6p, 6n, and 6e. This is C-12 (carbon 12).

• But carbon can also have 7 or 8 neutrons. Changing the neutrons changes the mass of the element but does not change the element.

These would be C-13 and C-14.