9th grade chemistry summary ch. 6-7

1. there are 2 kinds of bonding. they are ionic bonding and covalent bonding.
2. ionic bonding is type of bond that is formed between positively charged and negatively charged ions by the transfer of electrons.
3. covalent bonding is type of bond that is formed when two atoms are joined together by sharing electrons.
4. for the comparison of those bonding, you can check on pg. 94 textbook.
5. each carbon atom in diamond is bonded to four other carbon atoms by strong covalent bonds.
6. each carbon atom of graphite is joined to three other carbon atoms in the same plane.

physics summary for 9th grade

1.  There are several kinds of main pressures. they are air pressure, water pressure and force pressure.
2. Pressure is influenced by the area and the weight / force of object.
3. The narrower the area of an object, the greater the pressure will be.
4. according to Pascal, liquid will give the same pressure to all parts of isolated container.
5.  work means force that causes displacement.
6. there are 2 kinds of energy. they are kinetic energy and potential energy.
7. according to the Principle of energy conservation, energy can't be created nor destroyed. it can only be changed.
8. in formula, we can express the principle as Ek = Ep.
9. Power means the work done per time.