Basic Chemistry

Unit 4: Biochemistry

How matter and mass relateMatterMass 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.

The relationship between elements and atomsAll matter is composed of

atomsAtom: the smallest unit of

matterElement: a pure chemical

substance consisting of one type of atom.

The periodic table lists all the atoms that exist on Earth

Subatomic particles and their location: the anatomy of an atomThis 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 electronsProton: 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 chargeNeutron: Also in the nucleus, a neutron has no chargeElectron: an electron orbits the nucleus at high speeds, and has almost no mass. An electron has a negative electrical charge

More atomic informationAtomic number: the number of protons in the nucleus of an

atomAtomic number: the number of protons plus neutrons in

the nucleus of an atom, also called mass numberOn 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.

More subatomic informationOrbit: 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.

More subatomic informationIsotope: 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.

How different types of bonds form between atomsCompound: 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.

How different types of bonds form between atomsCovalent 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.

How different types of bonds form between atomsMolecule: 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.

How different types of bonds form between atomsIonic 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.

The three states of matterSolid: really tightly packed molecules or

atoms. They can barely move!

Solids have a definite shape and a definite volume

The three states of matterLiquid: 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.

The three states of matterGas: 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.

The three states of matterMaybe these pictures and the animation

will help you understand the three states.

http://www.harcourtschool.com/activity/states_of_matter/