1. Unit 4: Biochemistry
Basic Chemistry

2. How matter and mass relate
Mass vs Weight
Mass is the amount of matter in an object.
Weight is gravitational pull acting on matter. That’s why weiht can change on other planets, but mass cannot.
Vs.

3. The relationship between elements and atoms
All matter is composed of atoms
Atom: the smallest unit of matter
Element: a pure chemical substance consisting of one type of atom.
The periodic table lists all the atoms that exist on Earth

4. Subatomic particles and their location: the anatomy of an atom
This is the structure of an atom. The structure may vary by the number of protons, neutron, and electrons, but not their position
Nucleus: The center of the atom, the part with most of the mass, that contains neutrons and electrons
Proton: An atom is named after the number of protons in its nucleus. A proton and a neutron have roughly the same mass. Protons have a positive electrical charge
Neutron: Also in the nucleus, a neutron has no charge
Electron: an electron orbits the nucleus at high speeds, and has almost no mass. An electron has a negative electrical charge

5. More atomic information
Atomic number: the number of protons in the nucleus of an atom
Atomic number: the number of protons plus neutrons in the nucleus of an atom, also called mass number
On the periodic table, the number of electrons always equals the number of protons, making the atom neutral. We’ll see differences in this number, called ions, in the future.
Here’s some quick practice
Atomic number:
# of protons:
# of neutrons:
# of electrons:
Mass #:
Atomic number:
# of protons:
# of neutrons:
# of electrons:
Mass #:
See Practice page for more practice.

6. More subatomic information
Orbit: Electrons fly around the nucleus in specific patterns, called orbits
Energy Levels: Energy levels are made of the orbits, otherwise called orbitals. When an energy level is full, electrons must go to the next energy level.

7. More subatomic information
Isotope: Atoms can exist with varying numbers of neutrons. They don’t have a charge, so isotopes don’t change an atoms charge. All they do is change an atom’s mass.
Sometimes, changing the number of neutrons in an atom will make it radioactive, and Biologists use this to study biological functions, as seen below.

8. How different types of bonds form between atoms
Compound: two or more atoms combined in fixed proportions. Simplest example: H2
Hydrogen gas is on the left, where two hydrogen atoms combine to form H2.
Also shown here is water, on the right. Water is extremely important in biology.
Notice how there are two hydrogen atoms and one oxygen atom to form H2O.

9. How different types of bonds form between atoms
Covalent bonds: the sharing of electrons between atoms. REMEMBER: some atoms don’t share electrons equally, some atoms are bullies, and hog the electrons. Kind of like how share your clothes or video games with a younger sibling. You only let them have it sometimes, not all the time, and not more than you.
Hydrogen atoms are like twins that share equally, but oxygen is a bully. Oxygen does not share its electrons equally with either hydrogen.

10. How different types of bonds form between atoms
Molecule: once two or more atoms bond, they are not only called a compound, but they are also called a molecule.
Both compounds on the right can be called molecules too.
It’s one molecule of hydrogen gas, and one molecule of water.

11. How different types of bonds form between atoms
Ionic bonds: An ionic bond is when one atom completely steals an electron from another atom.
This is really important in your nerve cells, but we’ll learn more about that later in the year.
Notice how the chlorine atoms (big bullies) completely steal the electrons from the calcium atoms.
This forms ions: charged atoms or molecules. In the picture above, atoms, not molecules are shown.

12. The three states of matter
Solid: really tightly packed molecules or atoms. They can barely move!
Solids have a definite shape and a definite volume

13. The three states of matter
Liquid: these atoms or molecules can move freely, but always touch each other
Liquids have a definite shape, but not a definite volume. They can fit into any container.

14. The three states of matter
Gas: these molecules or atoms are moving so fast that they shake apart from one another, fly around, and sometimes collide.
Gases do not have a definite shape and do not have a definite volume.

15. The three states of matter
Maybe these pictures and the animation will help you understand the three states.