molecules and molecular compounds molecule – the smallest electrically neutral unit of a substance...
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Chapter 7Chapter 7
Chemical Names and Chemical Names and FormulasFormulas
Molecules and Molecular Compounds
•Molecule – the smallest electrically neutral unit of a substance that still has the properties of a substance.
•Molecular Compounds – Compounds composed of molecules.
Ions
• Ions – atoms or groups of atoms that have a positive or negative charge.– Ions form when an atom or group of atoms gains or loses an electron.•There are two different types of ions: anions and cations.
•Cation – any atom or group of atoms that has a positive charge.– Ex Sodium is a cation because
it has 11 protons and only 10 electrons. Sodium has a charge of 1+
•Na 1+ = Na+
(the number 1 is usually omitted)
Cations
• Anions – atoms or groups of atoms with a negative charge– Ex Chloride is an anion
because it has only 17 protons and 18 electrons.
Chloride has a charge of 1-
-- Cl 1- = Cl-
Anions
More Examples!
Cations Symbol Anions Symbol
Aluminum Al3+ Chlorate ClO3-
Cobalt(II) Co2+ Fluoride F-
Lead (IV) Pb4+ Hydroxide OH-
Magnesium Mg2+ Nitride N3-
Mercury (II) Hg 2+ Oxide O2-
Potassium K + Peroxide O22-
• Ionic compounds are composed of cations and anions–They are usually composed of a metal cation and a non-metal anion• Ex – Sodium Chloride
–sodium cation & chloride anion
Ionic Compounds
Chemical Compounds
•Chemical Formula – shows the kinds & numbers of atoms in the smallest representative unit of the substance.
Diatomic Compounds• They are non metallic elements
– Remember them!!!!! ( all 7 )•Hydrogen H2
•Fluorine F2
•Oxygen O2
•Nitrogen N2
•Chlorine Cl2
•Bromine Br2
•Iodine I2
• Molecular Formulas show the kinds and numbers of atoms present in the molecule of a compound.– Ex Ammonia = NH3
H N H
H
Molecular Formulas
**This structural formula shows that Ammonia has 3 atoms of Hydrogen and 1 atom of Nitrogen
Formula Units
•Formula Units represent the lowest whole number ratio of ions in a compound.– Ex Sodium Chloride
•1 Na+ to each Cl-
•The ratio of ions is 1:1• NaCl
• Magnesium Chloride– Contains magnesium cations (Mg2+) and
chloride anions (Cl-)– Ratio is 1:2
– Mg 2+ Cl –
-- MgCl2
More Examples and Forming Compounds….
•Aluminum Chloride• Contains aluminum cations
(Al3+) and chloride anions (Cl-)• Ratio is 1:3
Al 3+ Cl -
-- AlCl3
Type I Binary Ionic
• Group “A” metal – non metal– Name of metal + name of non metal +ide
– Ex – NaCl – Sodium Chloride
– CaBr2 – Calcium Bromide
– Al2O3 – Aluminum Oxide
•Transition Metal – non metal–Name of metal + Roman Numeral + Non Metal + ide•Exceptions ( Ag+, Zn2+, Cd2+)•Ex
•Cu2O – Copper(I) Oxide
•HgI2 – Mercury (II) Iodide
Type II Ternary Ionic
• Group “A” Metal-Radical–name of metal + name of radical
• Transition Metal-Radical–name of metal+ Roman Numeral+ name of radical
•Non Metal – Non Metal•Use Prefixes
–Mono - Hexa–Di - Hepta–Tri - Octa–Tetra - Nona–Penta - Deca
–Ex PCl 3 - Phosphorous Tri Chloride
SF6 - Sulfur Hexa Flouride
Acids
•Give off H+ ions when dissolved in H2O
•Acids in form of HX
•where X = mono-atomic or poly-atomic ions
3 Rules1) If X ends in - ide , acid
name begins with the prefix hydro, and the stem of the anion has the suffix - ic followed by the word acid.Ex: HCl X =
Chloride Hydrochloric Acid
•2) If X ends in -ite , the acid name is the stem of the anion with the suffix -ous , followed by the word acid.
–Ex: H2SO3 X= Sulfite
»Sulfurous Acid
•3) If X ends in - ate, the acid name is the stem of the anion with the suffix - ic, followed by the word acid.
–Ex: HNO3 X= Nitrate
»Nitric Acid
Examples
•HClO3 - Chloric Acid
•HCN - Hydrocyanic Acid
•H3PO4 - Phosphoric Acid
•HF - Hydroflouric Acid
•HC2H3O2 -Acetic Acid
More Examples
•H2SO4 - Sulfuric Acid
•HNO2 - Nitrous Acid
•Hydroiodic Acid - HI
•Chromic Acid - H2CrO4
•Chlorous Acid - HClO2