Unit 2: Chemistry of Life 🧪⚛️🧬
This unit explains the chemistry that makes life possible. Every living thing is built
from atoms, molecules, water, and large biological compounds called
macromolecules.
1. Matter and Atoms
Matter
Matter is anything that has:
● Mass
● Volume
Everything in biology is made of matter.
Examples:
● Cells
● Water
● Air
● Proteins
2. Atoms ⚛️
Atoms are the smallest units of matter.
Structure of an Atom
,Particl Charge Location
e
Proton Positive Nucleus
(+)
Neutro Neutral Nucleus
n (0)
Electro Negative Electron
n (-) cloud
Important Facts
Atomic Number
Number of protons.
Example:
Carbon has 6 protons → atomic number = 6
Mass Number
Protons + neutrons.
Example:
Carbon:
, ● 6 protons
● 6 neutrons
Mass number = 12
Isotopes
Atoms of the same element with different numbers of neutrons.
Example:
Carbon-12 vs Carbon-14
Some isotopes are radioactive.
Uses:
● Medicine
● Carbon dating
Elements Essential for Life
About 96% of living matter is made from:
Elemen Symb
t ol
Carbon C
Hydrog H
en
This unit explains the chemistry that makes life possible. Every living thing is built
from atoms, molecules, water, and large biological compounds called
macromolecules.
1. Matter and Atoms
Matter
Matter is anything that has:
● Mass
● Volume
Everything in biology is made of matter.
Examples:
● Cells
● Water
● Air
● Proteins
2. Atoms ⚛️
Atoms are the smallest units of matter.
Structure of an Atom
,Particl Charge Location
e
Proton Positive Nucleus
(+)
Neutro Neutral Nucleus
n (0)
Electro Negative Electron
n (-) cloud
Important Facts
Atomic Number
Number of protons.
Example:
Carbon has 6 protons → atomic number = 6
Mass Number
Protons + neutrons.
Example:
Carbon:
, ● 6 protons
● 6 neutrons
Mass number = 12
Isotopes
Atoms of the same element with different numbers of neutrons.
Example:
Carbon-12 vs Carbon-14
Some isotopes are radioactive.
Uses:
● Medicine
● Carbon dating
Elements Essential for Life
About 96% of living matter is made from:
Elemen Symb
t ol
Carbon C
Hydrog H
en
