How Elements Bond

1. How Elements Bond Chapter 6 Section 2

2. Ionic Bonds • Some atoms form bonds by losing or gaining an electron- these are called ions • Because electrons are negatively charged particles; If an Ion gains an electron it will have a negative charge, negative ion • If an ion loses an electron the ion will have a positive charge, positive ion

3. Positive/ Negative charged ions • If an ion has a positive or negative charge it will be written with a superscript of + or -. • If the ion has more than one positive or negative charges then a number should follow the + or – • Example: Sodium with a positive charge should look like Na+

4. More Gains and losses • An ionic bond forms when a positively charged ion and a negatively charged ion are attracted to each other • Sometimes atoms may have more than one electron being gained or lost that is represented by a superscript +n, where n is the number of electrons lost or gained • For our purposes Ionic bonds mainly happen between nonmetals and metals

5. Metallic Bonding-Pooling • Metals can form bonds with other metals by pooling their electrons. • Electrons that are shared between metals move freely among all the ions, they are not attached to any one atom in particular but being shared by all atoms • Why are electrical wires made out of metal?

6. Covalent Bonds- Let’s be friends and Share • Some atoms have a lot of outer electrons, since it is hard to gain that many to make a stable outer shell, many atoms will share their electrons- these bonds are called covalent • Most nonmetals form covalent bonds between other nonmetals

7. More sharing is necessary • A molecule is the neutral particle formed when atoms share electrons • There are no ions present, because there is no gaining or losing of electrons • Look at a hydrogen atom, the dot diagram for hydrogen has one dot, to complete the outer shell hydrogen needs to have at least 2 electrons, • so hydrogen shares it’s electron with another hydrogen atom to make a stable molecule, H2

8. Double and triple bonds • So far all we have talked about were single bonds, one electron being shared by an atom • Sometimes atoms will share more than just one electron with another atom. • When two pairs of electrons are involved in a covalent bond the bond is called a double bond • When three pairs of electrons are involved in a covalent bond the bond is called a triple bond

9. Polar and Nonpolar- molecules not bears • Some atoms are nicer than others, meaning they are easier to share with! • A polar bond means that electrons are shared unevenly. Water is polar molecule because the hydrogen side of the oxygen molecule has a partial positive charge, where the other side has a partial negative charge

10. More polar and nonpolar • Most of the time, you can tell if a molecule is polar or nonpolar by its symmetry. Remember that symmetry is when an object looks the same after it has been cut in half • If a molecule is symmetrical no matter how the plane divides it, it is a nonpolar molecule • Lets talk about the bonds between hydrogen and oxygen in water molecules.

11. Chemical Shorthand • We have already had much experience with the symbols we use for atoms, scientists also have symbols for compounds • Instead of writing all of the Lewis dot diagrams every time, scientists usually just use numbers and symbols.

12. Chemical Formula’s • A combination of symbols and numbers to show which elements are present in a compound and an how many atoms there are. • Such as for water, they use H2O, where the two after the H meaning 2 hydrogen atoms and one oxygen atom • How many atoms does a molecule of sodium hydroxide contain? NaOH

13. What kind of bond is it? • If you combine nitrogen and oxygen, what kind of bond would form? • How about sodium and iodine? • Calcium and Gallium?