The Chemistry of Life Atoms and Elements Chapter 6

Atoms are the basic units of all matter.

An atom is the smallest particle of an element that has the characteristics of that element.

The nucleus is the center of an atom. The nucleus contains positive protons (+) and neutral neutrons (0). The electron cloud is the area surrounding the nucleus it contains negative electrons (-). Atoms are composed of 3 sub-atomic particles:

An element is a substance that can not be broken down into simpler chemical substances.

Everything is made of substances called elements.

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

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 #

Atomic number The atomic number is equal to the number of protons that an atom has. Ex. Silver has an atomic number of 47 and therefore has 47 protons

Atomic mass The atomic mass is the number of protons and neutrons added together. How do you figure how many neutrons there are? Atomic mass - atomic number = number of neutrons!

Atoms of the same element that have different numbers of neutrons are called isotopes. Isotopes still have the same chemical properties as the element! Ex: Carbon normally has 6p, 6n, and 6e. This is C-12 (carbon 12). But wait! Carbon can also have 7 or 8 neutrons! *These would be C-13 and C-14.

Ions If an atom loses/gains electrons, it becomes an ION and will have a charge Ex. Na+1 (lost an electron) Cl -1 (gained an electron) Do you want to hear a funny joke??

Fun fact: Carbon, hydrogen, oxygen, and nitrogen are the four elements that make up more than 96% of the mass of a human body