A. Elements
➢ All life forms made up of matter
- All matter made up of elements
■ Elements
● Substances that cannot be broken down into smaller substances by chemical means
- All matter made up of elements
B. Essential Elements of Life
➢ 96% of the mass of all living things made up of 4 elements:
- $\text{Oxygen (O)}$
- $\text{Carbon (C)}$
- $\text{Hydrogen (H)}$
- $\text{Nitrogen (N)}$
➢ Other elements (collectively 4% of biomass)
- $\text{Calcium (Ca)}$
- $\text{Phosphorus (P)}$
- $\text{Potassium (K)}$
- $\text{Sulfur (S)}$
- $\text{Sodium (Na)}$
- $\text{Chlorine (Cl)}$
- $\text{Magnesium (Mg)}$
➢ Trace elements
- $\text{Iron (Fe)}$
- $\text{Iodine (I)}$
- $\text{Copper (Cu)}$