What is Biology?

Biotic means living.

Abiotic means non-living.

How do we know if something is living?

If it’s made up of cells

If it maintains internal balance (also known as homeostasis).

If it’s able to reproduce

All organisms grow and develop in their lifetime.

The ability to react or respond to the environment.

Must be able to make or use energy (metabolism).

Able to pass down their traits to their offspring.

Must be able to adapt.

Are viruses alive?

Overall, viruses are not alive since they do not have all characteristics of living things.

So, if something is living, it must possess all of the listed characteristics above.

Intro to Chemistry

Like all matter, living things are made up of atoms.

Elements are substances made up of one type of atom.

Carbon is the most abundant atom in living organisms.

Atoms contain:

Protons (+), Found in the nucleus

Neutrons (0), Found in the nucleus

Electrons (-), Found around the nucleus

Quick note:

Why do Iron and Gold have different atomic letters than the words?

Because they were found in a different country who spoke a different language.

Parts of an element:

The number on the top is called the Atomic Number, which is the number of protons (and the number of electrons).

The number on the bottom is the Atomic Mass, which is the number of protons + the number of neutrons.

In this element, there are 6 protons, 6 neutrons, and 6 electrons because we know that the top number represents the number of protons and electrons. However, since the atomic mass is the number of protons PLUS the number of neutrons, we can subtract 12 - 6 = 6.

On the outer ring of an element is the number of electrons:

1st ring can have 2 electrons.

2nd ring can have 8 electrons.

3rd ring can have 8 electrons.

4th ring can have 18 electrons.

Valence electrons: the number of electrons in the outermost ring.

Energy levels: number of rings around the nucleus.

Bonding Notes

The goal of every atom is to have its outer ring full

Every atom gets its outer ring full with 8 electrons; except for hydrogen and helium.

If the outer ring of an atom is full, the atom is stable (”happy”).

If the outer ring is NOT full, the atom forms a bond (or relationship) with another atom.

Atoms form bonds with other atoms to become stable.

Covalent Bonds: atoms share electrons

Ionic Bonds: electrons are transferred, Ions: atoms with a charge