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Chapter 15
Ionic Bonding
| Term | Definition |
|---|---|
| valence electrons | outermost "s" and "p" electrons in an atom |
| electron dot diagrams | depicts valence electrons |
| lewis dot diagram | does not distinguish between "s" and "p" electrons, fills spots one at a time in all four sides (orbitals) |
| cation | a positively charged ion that is formed when an atom loses one or more electrons |
| anion | a negatively charged ion that is formed when an atom gains one or more electrons; monatomic anions are named with an "-ide" ending |
| noble gases | (1) most stable because outermost "s" and "p" subshells are filled (2) of lowest energy and chemical reactivity because of their stable electron configurations |
| monatomic ion | a single atom ion |
| polyatomic ion | a group of atoms with a charge |
| octet rule | states that atoms react by changing the number of their electrons to acquire the stable electron structure of noble gases (full outer shell) |
| metals obey the octet rule by ___ to form ___ | losing electrons...cations |
| nonmetals obey the octet rule by ___ to form ___ | gaining electrons...anions |
| ionic bond | the force of attraction that binds oppositely charged ions together |
| HOW ARE IONIC BONDS FORMED | FIND THE ANSWER TO THIS |
| formula unit | collection of independent ions that bond together to form a crystal and has the following properties: (1) composed of cations and anions (2) have a neutral charge (3) held together by ionic bonds |
| solid crystalline structure | a repeating three-dimensional pattern |
| coordination number | the number of oppositely charged ions touching a single ion |
| (1) the shape of a crystal is determined by the ___ and ___ of the ions | charge...size |
| (2) brittle | when a force is applied to an ionic compound, like charges are forced together and in response, the like charges repel and the crystal chatters into many smaller crystals |
| (3) high melting points | determined by the strength of the bond...the stronger the bond, the higher the melting point |
| (4) not flammable | crystal will NOT combust when exposed to direct heat |
| (5) readily soluble in water | ionic compounds easily dissolve in water because they dissociate (separate into individual ions when dissolved in water) |
| (6) does NOT conduct electricity as a solid | must have free movement of charge to conduct electricity crystal structure means ions are "locked" into a fixed position and unable to move freely, thus do not conduct electricity |
| (7) conducts electricity as a liquid | when melted, ionic bonds break, which frees ions and allows them to move freely and thus, conduct electricity |
| (8) conducts electricity as a solution | because ionic compounds dissociate when dissolved in water, the ions are free to move around and thus conduct electricity |
| representative metals | the smallest particle of a substance that keeps the identity of that substance, and come in three types |
| atom | representative part for an ELEMENT |
| formula unit | the representative particle for an IONIC COMPOUND because it is the smallest particle of an ionic compound that keeps the identity of that compound |
| molecule | the representative part for a MOLECULAR COMPOUND |
| **an ionic compound consists of a cation and an anion | ... |
| metallic bond | the attraction between the free floating valence electrons (sea of electrons) and fixed positive nuclei of the metal atoms |
| **metallic bonds are non-directional | ... |
| properties of metals: | ... |
| (1) malleable (able to be smashed into thin sheets) (2) ductile (able to be put into wire) | atoms can slide over one another because metallic bonds are non-directional |
| (3) good conductors of heat (4) good conductors of electricity | sea of electrons allows free floating valence electrons |
| (5) crystalline structure | 1. face centered cubic 2. hexagonal closest packing 3. body centered cubic 4. coordination number |
| coordination number | the number of oppositely charged ions that touch an ion |
| alloys | a solution (mixture combined physically) of metals, which are homogeneous |
| types of alloys: | |
| substitutional alloy | metal atoms mix because they are the same size |
| interstitial alloy | component metals are different sizes, essentially, smaller ones go into bigger ones |