Ionic & Covalent Bonding Chapter 5 Section 2

Why do atoms want to bond? Atoms want to be STABLE. – Goal: to have an electronic structure close to that of a Noble Gas. The type of bond that atoms form affects the substances properties. FK

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FK Fluorine now has a total of 10 electrons = Neon Potassium now has a total of 18 electrons = Argon +-

There are 3 types of bonding: 1.Ionic 2.Covalent 3.Metallic

Ionic Bonds Bonds formed between oppositely charged ions by a transfer of electrons.

Formation of Ions from Metals Ionic compounds result when metals react with nonmetals Metals lose electrons to match the number of valence electrons of their nearest noble gas Positive ions form when the number of electrons are less than the number of protons: Cation Li + Group 1 metals  ion 1+ Mg 2+ Group 2 metals  ion 2+ Al 3+ Group 13 metals  ion 3+

Nonmetals gain electrons to match the number of valence electrons of their nearest noble gas. Negative ions form when the number of electrons are more than the number of protons: Anion Cl - Group 17 metals  ion 1- S 2- Group 16 metals  ion 2- P 3- Group 15 metals  ion 3- Ionic compounds will conduct electricity when melted or dissolved in water. Ionic compounds have a very high melting point.

Formation of Sodium Ion Sodium atom Electron Exchange Sodium ion Na minus 1e   Na ( = Neon) (2 in 1 st level, 8 in 2 nd (2 in 1 st, 8 in 2 nd ) level, 1 in 3 rd level) 11 p + 11 p + 11 e - 10 e

Group 1 Group 2 Group 13 Group 14 Group 15 Group 16 Group 17 Group Or

Covalent Bonds Bond formed by the sharing of electrons.

Covalent bonds are formed between two nonmetals. Covalent compounds usually have low melting points. Electrons can be shared equally (nonpolar) or unequally (polar). The number of electron pairs shared can also vary.

when electrons are shared equally NONPOLAR COVALENT BONDS

Cl

This is called a SINGLE BOND (The sharing of one pair of electrons = 2 electrons)

O O = This is an example of a DOUBLE BOND (The sharing of two pairs of electrons = 4 electrons) O O

This is called a TRIPLE BOND (The sharing of three pairs of electrons = 6 electrons)

when electrons are shared but shared unequally POLAR COVALENT BONDS

In this type of bond, electrons are attached to the nucleus of one atom more than the other. – Therefore, unequal sharing occurs. Usually, electrons are more attracted to atoms of elements that are located to the right and closer to the top of the periodic table.

METALLIC BONDS

The bonding of a metal to a metal. The attraction between one atom’s nucleus and another atom’s electrons which packs the atoms closely together. Properties: – Flexible = can stretch and bend without breaking. Metallic Bonds are flexible because their atoms can slide past each other without breaking. – Good conductor of electricity. Atoms are free moving – This is why metallic bonds can conduct electricity. Electrons in the outer level overlap.

Polyatomic Ions Have both Covalent and Ionic bonds. – This means that the bond is technically Covalently bonded that have either LOST or GAINED electrons. Polyatomic anions are made of Oxygen. – ate: ions with one or more Oxygen. – ite: ions with 1 less Oxygen.

-ate -2 4 SULFATE

-ite -2 3 SULFITE

Transition Metals have many different charges. Roman numerals in parenthesis following a cation to show the charge. – i.e. Copper (I) ion Copper (II) ion Titanium (II) ion Titanium (III) ion Titanium (IV) ion