2. Atoms, Elements, and Compounds

3. Chapter Fifteen: Molecules and Compounds
15.1 Compounds and Chemical Bonds
15.2 Electrons and Chemical Bonds

4. Investigation 15A Chemical Bonds
How do atoms form chemical bonds with other atoms?

5. 15.1 Compounds and chemical bonds
A compound contains two or more different elements that are chemically bonded together.

6. 15.1 Compounds and chemical bonds
A mixture contains two or more elements and/or compounds that are not chemically bonded together.

7. 15.1 Molecules and covalent bonds
A chemical bond forms when atoms transfer or share electrons.
A covalent bond is formed when atoms share electrons.

8. 15.1 Chemical formulas and diagrams
Molecules are represented by a chemical formula.
The chemical formula tells you the precise number of each kind of atom in the molecule.

10. 15.1 Structure and function
The properties of a compound depend MUCH more on the exact composition and structure (shape) of its molecule than on the elements of which it is made.

11. 15.1 Ionic bonds
Ionic bonds are bonds in which electrons are transferred from one atom to another.
Sodium and chlorine form an ionic bond because the positive sodium ion is attracted to the negative chloride ion.

13. 15.1 Why chemical bonds form
It takes energy to separate atoms that are bonded together.
The same energy is released when chemical bonds form.
Atoms form bonds to reach a lower energy state.