molecules and ions. chemical bonds atoms are held together in compounds by chemical bonds

21
Molecules and Ions

Upload: shannon-floyd

Post on 04-Jan-2016

219 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Molecules and Ions

Page 2: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Chemical bonds

• Atoms are held together in compounds by chemical bonds

Page 3: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Covalent Bonds

• If atoms are held together by sharing electrons then this is known as a chemical bond

• Covalent bonds form molecules• Molecules are represented by chemical

formulas, H2O• Or by structural formulas, H – O – H• Or by models

Page 4: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Ionic Bonds

• If electrons are transferred then an ionic bond is formed

• NaCl• Na ----- Na+ + e-• Cl + e- ------Cl-

Page 5: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Periodic Table

• Lots of info• Charge• Atomic Mass• Atomic Number• Metals and Non-Metals• Alkali Metal (I), Alkali Earth Metals (II),

Halogens (VII), Noble Gases (VIII), Trans. Met.

Page 6: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Periods

• Horizontal rows on PT

Page 7: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Groups

• Columns on PT

Page 8: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Naming Simple Compounds

• Binary Compounds• These are compounds that are composed of

two types elements

Page 9: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Binary Ionic Compounds (Type I)

• These compounds contain a positive ion (cation) and a negative ion (anion)

• Na+, cation• Cl-, anion

Page 10: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Rules for Naming Type I Binary Ionic Compounds

• Cation always named first• Anion always named second• A monoatomic cation is named as the element

is named, Na+ is sodium• A monoatomic anion is named as the element

but as an –IDE, so Cl- is ChlorIDE• See Table 2.3

Page 11: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Name These

• CsF• Cesium Flouride• AlCl3• Aluminum chloride• LiH• Lithium Hydride

Page 12: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Binary Ionic Compounds (Type II)

• Many cations can form more than one type of ions

• Especially the Transtition Metals• Use Roman Numerals to indicate charge• Ion of higher charge ends in –ic• Ion of lower charge end in –ous• Fe (II) ferrous, Fe(III) ferric

Page 13: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Naming Type II Binary Compounds

• CuCl• Copper (I) chloride• HgO• Mercury (I) oxide• Fe2O3• Iron (III) oxide

Page 14: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Write the formula for these

• Manganese (IV) oxide• MnO2• Lead (II) chloride• PbCl2

Page 15: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

• If the cation only has one possible ion thenn DO NOT USE a roman numeral

• It is understood what the charge on the ion is

Page 16: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Polyatomic Ions

• Some ions are made up of two or more atoms• These are known as polyatomic ions• SO4 -2, OH-, NO3-• See Table 2.5• Must know formula and charge• Use flashcards

Page 17: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Name these compounds

• Na2SO4• Sodium sulfate• KH2PO4• Potassium dihydrogen phosphate• Na2CO3• Sodium carbonate

Page 18: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

WriteFormulas

• Sodium Hydrogen Carbonate• NaHCO3• Potassium perchlorite• KClO4

Page 19: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Binary Covalent Compounds (Type III)

• These are compounds formed between two non-metals

Page 20: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

Rules for Naming Binary Covalent Compounds (Type III)

• The first element in the formula is named first• The second is named as if it was an anion• Prefixes denote the number of atoms present• Mono- is never used for the first element as it

is assumed.• Mono- is used for the second element, Co• See p. 63

Page 21: Molecules and Ions. Chemical bonds Atoms are held together in compounds by chemical bonds

• Review