 Electrons in the highest occupied energy level of an element’s atoms  To find the number of valence electrons in an atom of a representative element, simply look at its group number. If it’s in group 1 or 2. If it is in groups subtract 10 to find the number of valence electrons.

 In the formation of compounds, atoms tend to achieve the electron configuration of a noble gas.  Atoms either gain, lose, or share electrons to form compounds.

Loses an e- -An atom’s loss of valence electrons produces a cation, or a positively charged ion.

 Metals – lose valence e- easily  Transition metals – have 2 valence e-, usually lose those two to form 2+ ions, but can also lose d electrons to form other ions

 Nonmetals easily gain e - to form negative ions to get to 8 valence e - Gains an e- Chloride ion

-Nonmetals usually gain e - Some can gain or lose, but will gain most often

- The lowest whole-number ratio of ions in an ionic compound.

 When oppositely charged ions attract, electrostatic force that holds them together = ionic bond  Compounds containing ionic bonds = ionic compounds  Electrons are transferred from cations to anions  Bonds formed between metals and nonmetals (or contain a polyatomic ion)

Na· 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 3p 5 RESULTS IN Na + 1s 2 2s 2 2p 6 1s 2 2s 2 2p 6 3s 2 3p 6

 Most ionic compounds are crystalline solids at room temperature.  Arranged in repeating three-dimensional patterns  Ionic compounds generally have high melting points  Large attractive forces result in very stable structures

 Ionic compounds can conduct an electric current when melted or dissolved in water.  When ionic compounds are dissolved in water the crystalline structure breaks down. This allows the ions to move freely which results in conductivity.

 The positive Na ions move to the cathode and the negative Cl ions move to the anode.

 Metals are good conductors because the valence electrons are able to flow freely within them.  Valence electrons of metals can be thought of as a sea of electrons.

 The ductility and malleability of metals can be explained by the mobility of electrons in metals.  When a metal is subjected to pressure, the cations easily slide past each other like a ball bearing immersed in oil. If an ionic crystal is stuck with a hammer the cations are pushed together, repel, and the crystal shatters.