Atoms chemically bond in an attempt to feel stable like noble gases. They do this by either filling their valence shells or getting rid of the electrons in their valence shell.

Just like the 26 letters of alphabet combine to form words, the 100+ elements combine to form compounds. A compound is formed when 2 or more elements chemically combine (go through a chemical change).

Lewis dot diagrams are a way to show the number of valence electrons in an atom. They are represented by the element’s symbol surrounded by dots (one for each valence electron).

Li lithium N nitrogenneon Ne

A. X would be the electron dot formula for a. sodium (Na) b. calcium (Ca) c. aluminum (Al) B. X would be the electron dot formula a. boron (B) b. nitrogen (N) c. oxygen (O)

Lewis dot diagrams can be used to represent ions: Sodium atom Sodium ion Na  – e   Na + (feels like Ne) 11 p + 11 p + 11 e - 10 e

Fluorine atom Fluorine ion : F : + e   : F : - (feels like Ne) 9 p + 9 p + 9 e - 10 e

An ionic bond forms when one atom transfers an electron to another atom. Occurs when a metal reacts with a non- metal. The number of electrons lost must be equal to the number of electrons gained.

During ionic bonding, metals lose electrons and nonmetals gain electrons. The atoms in an ionic compound are held together by the strong attraction of the positive and negative ions.

Great conductors of electricity when dissolved in water Have very high melting points Most are solids at room temperature

A. How many valence electrons does aluminum (Al) have? a. 1b. 2c. 3 B. How many electrons does Al want to gain or lose? a. lose 3e - b. gain 3e - c. gain 5e - C. What is the charge of an Al ion? a. 3 - b. 5 - c. 3 +

D. Al is most likely to form an ionic bond with a. oxygen (O) b. nitrogen (N) c. fluorine (F) E. Explain your answer to D. F. Ionic compounds have what kind of charge? a. negative b. positive c. no charge

A covalent bond is formed when electrons are shared between 2 atoms. Occurs between two or more nonmetals. A molecule is an individual group of covalently bonded atoms. (Oxygen and hydrogen bond covalently to form water molecules.)

Poor conductors of electricity Have low melting points Mostly liquids and gases at room temperature (any that are solids are the consistency of plastics)

A. Covalent bonds are formed when atoms _____ electrons. a. give up b. take on c. share B. Oxygen (O) would most likely form a covalent bond with a. sodium (Na) b. nitrogen (N) c. calcium (Ca) C. Explain your answer to B.