Atoms and their Interactions

• Everything is composed of elements.
• Element - a substance that can’t be broken down into simpler chemical substances
• On Earth, 92 elements occur naturally.
• 25 elements are essential for life
• 96% of the human body is composed of only C,H,O and N
• Trace elements are only found in small amounts within an organism

The Building Blocks of Elements

• Elements are composed of atoms
• Atom - the smallest particle of an element that has the characteristics of an element.
• Each element has distinct properties based on its structure
• Nucleus - the center of an atom, which is composed of protons (+) and neutrons (0).
• An electron (-) cloud is then formed around the nucleus

Electron Energy Levels

• It is impossible to pinpoint the exact location of an e-, hence why we say it is located within an e- cloud.
• Electrons travel around the nucleus in certain energy levels
• Each energy level can hold a different number of e- which also play a role in an elements characteristics

Isotopes of an Element

• Atoms of an element can sometimes differ in their number of neutrons, we call this an isotope.

Compounds