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Nomenclature

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Nomenclature Honors Chemistry Mrs. Partridge Predicting Ionic Charges Group 15: Gains 3 electrons to form 3- ions N3- P3- As3- Nitride Phosphide Arsenide ... – PowerPoint PPT presentation

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Title: Nomenclature


1
Nomenclature
  • Honors Chemistry
  • Mrs. Partridge

2
Chemical Names and Formulas
  • Every substance is either an element or a compound

3
Chemical Names and Formulas
  • In nature, only the noble gas elements tend to
    exist as isolated atoms
  • Noble gases are monatomic consisting of single
    atoms

4
Chemical Names and Formulas
  • A compound consists of more than one kind of atom
  • A compound is either molecular or ionic in nature

5
Molecules and Molecular Compounds
  • A molecule is the smallest electrically neutral
    unit of a substance that still has the properties
    of the substance

6
Molecules and Molecular Compounds
  • Molecules are made up of 2 or more atoms that act
    as a unit
  • Diatomic molecules are composed of 2 atoms (O2)
  • Triatomic molecules are composed of 3 atoms (O3
    ozone)

7
Molecules and Molecular Compounds
  • Atoms of different elements combine chemically to
    form compounds
  • Compounds composed of molecules are called
    molecular compounds

8
Molecules and Molecular Compounds
  • Molecular compounds tend to have relatively low
    melting and boiling points

9
Molecules and Molecular Compounds
  • Most molecular compounds are composed of 2 or
    more nonmetals
  • The molecules of a given molecular compound are
    all the same

10
Ions and Ionic Compounds
  • Not all compounds are molecular. Many compounds
    are composed of particles called ions
  • Ions are atoms or groups of atoms that have a
    positive or negative charge

11
Ions and Ionic Compounds
  • Ions conduct electricity

12
Ions and Ionic Compounds
  • Metals tend to form ions by losing one or more
    electrons
  • A cation is any atom or group of atoms that has a
    positive charge

13
Ions and Ionic Compounds
  • For metallic elements, the name of a cation is
    the same as the name of the element

Monatomic cation name of the element Ca2
calcium ion
14
Ions and Ionic Compounds
  • A metallic atom is chemically different than a
    metallic ion

Na atom is highly reactive
15
Ions and Ionic Compounds
  • Nonmetals tend to form anions by gaining one or
    more electrons

16
Ions and Ionic Compounds
  • An anion is an atom or group of atoms that have a
    negative charge

17
Ions and Ionic Compounds
  • The name of an anion of a nonmetal is NOT the
    same as the element name.
  • The name typically ends in ide
  • Sulfur Sulfide

18
Ions and Ionic Compounds
  • Compounds composed of cations and anions are
    called ionic compounds

19
Ions and Ionic Compounds
  • Although they are composed of ions, ionic
    compounds are electrically neutral
  • The TOTAL positive charge the TOTAL negative
    charge

20
Ions and Ionic Compounds
  • Ionic compounds are usually solid crystals at
    room temperature, and melt at high temperatures

21
Chemical Formulas
  • A chemical formula shows the kinds and numbers of
    atoms in the smallest representative unit of the
    substance

22
Chemical Formulas
  • If the molecule has more than one atom of the
    element, a subscript is used
  • Cl2
  • subscript

23
Molecular Formulas
  • The chemical formula of a molecular compound is
    called a molecular formula
  • CO2

24
Molecular Formulas
  • Molecular formulas show the composition of a
    molecule, NOT the structure

25
Formula Units
  • Chemical formulas can also be written for ionic
    compounds
  • Formula units are used to represent an ionic
    compound.
  • A formula unit is the lowest whole-number ration
    of ions in the compound

26
Formula Units
  • Ionic charges are used in the criss-cross method
    to derive the correct formula, but they are not
    shown in the formula
  • Mg2 Cl-1
  • MgCl2

27
Monatomic Ions
  • For monatomic ions, the ionic charges can be
    determine by using the periodic table

28
Predicting Ionic Charges
Group 1
Lose 1 electron to form 1 ions
H
Li
Na
K
29
Predicting Ionic Charges
Group 2
Loses 2 electrons to form 2 ions
Be2
Mg2
Ca2
Ba2
Sr2
30
Predicting Ionic Charges
Group 13
Loses 3 electrons to form 3 ions
B3
Al3
Ga3
31
Monatomic Ions
  • Metallic elements tend to LOSE electrons. Metals
    in group IA, 2A, and 3A lose electrons when they
    form cations

32
Monatomic Ions
  • The ionic charge is positive and is NUMERICALLY
    equal to the group number

33
Predicting Ionic Charges
Group 14
Lose 4 electrons or gain 4
electrons?
Neither! Group 13 elements rarely form ions.
34
Predicting Ionic Charges
Nitride
N3-
Group 15
Gains 3 electrons to form 3- ions
P3-
Phosphide
As3-
Arsenide
35
Predicting Ionic Charges
Oxide
O2-
Group 16
Gains 2 electrons to form 2- ions
S2-
Sulfide
Se2-
Selenide
36
Predicting Ionic Charges
F1-
Br1-
Fluoride
Bromide
Group 17
Gains 1 electron to form 1- ions
Cl1-
Chloride
I1-
Iodide
37
Monatomic Ions
  • The numerical charge of an ion of a Group A
    nonmetal is determined by subtracting the group
    number from 8
  • Nonmetals tend to gain electrons and form anions,
    so the sign of the charge is negative

38
Predicting Ionic Charges
Group 18
Stable Noble gases do not form ions!
39
Monatomic Ions
  • Noble gases do not form ions

40
Predicting Ionic Charges
Groups 3 - 12
Many transition elements
have more than one possible oxidation state.
Iron(II) Fe2
Iron(III) Fe3
41
Predicting Ionic Charges
Groups 3 - 12
Some transition elements
have only one possible oxidation state.
Zinc Zn2
Silver Ag
42
Monatomic Ions
  • Many transitional metals are capable of forming 2
    cations. There are 2 ways to name them. The
    stock name uses a Roman numeral (I, II, III) in
    parentheses after the symbol indicating the
    charge.

43
Monatomic Ions
  • The classical naming system uses a root word with
    different suffixes
  • The suffix ous is used to name the cation with
    the lower of the 2 ionic charges
  • Fe2 is ferrous ion
  • The suffix ic is used with the higher of the 2
    ionic charges
  • Fe3 is ferric ion

44
Polyatomic Ions
  • Polyatomic ions are tightly bound groups of atoms
    that behave as a unit and carry a charge

45
Polyatomic Ions
  • MOST polyatomic ions end in ite or-ate. 3
    exceptions ammonium ion (NH4), cyanide ion
    (CN-) and hydroxide ion (OH-)
  • The charge of each polyatomic ion in a given pair
    is the same, but the ite ending indicates one
    less oxygen atom than the ate ending
  • NO3- nitrate NO2- nitrite
  • SO42- sulfate SO32- sulfite

46
Writing Formulas for Binary Ionic Compounds
  • Compounds composed of 2 elements are called
    binary compounds
  • H2O
  • When writing the formula for a binary compound,
    the cation is ALWAYS written first

47
Writing Formulas for Binary Ionic Compounds
  • The positive charge the negative charge. The
    net ionic charge must 0.
  • Written using the criss-cross method, but
    remember to use the LOWEST whole number ratio of
    ions. Ca2 and S2- would criss-cross to Ca2S2,
    but the lowest whole number ratio of ions reduces
    to CaS

48
Naming Binary Ionic Compounds
  • Name the compound by naming the ions in the order
    written in the formula
  • Na and Br- NaBr
  • sodium bromide sodium bromide
  • ion ion

49
Naming Binary Ionic Compounds
  • The name of the transition metal that has more
    than one ionic charge must include a Roman
    numeral (or the proper suffix)
  • Fe2 and Cl- FeCl2
  • iron (II) chloride iron (II) chloride
  • ion ion
  • Ferrous chloride ferrous chloride
  • ion ion

50
Ternary Ionic Compounds
  • Ternary compounds contain 3 elements
  • CaCO3 calcium carbonate
  • 1 2 3

51
Ternary Ionic Compounds
  • Write the formula for each ion in the order
    listed in the name (cation followed by anion),
    then use the criss-cross method to determine the
    subscripts. If more than 1 polyatomic ion is
    needed, place the polyatomic ion formula in
    parentheses, followed by a subscript showing the
    number needed
  • Mg2 and OH- Mg(OH)2
  • magnesium hydroxide magnesium
  • ion ion hydroxide
  • When naming ternary ionic compounds from their
    formulas, you must recognize the polyatomic ions
    first

52
Binary Molecular Compounds
  • Binary molecular compounds are composed of 2
    nonmetals
  • They are composed of molecules, NOT IONS, so the
    criss-cross method will NOT work
  • Use prefixes to tell how many atoms are present

53
Binary Molecular Compounds
Prefix Mono- Di- Tri- Tetra- Penta-
Number 1 2 3 4 5
Prefix Hexa- Hepta- Octa- Nona- Deca-
Number 6 7 8 9 10
54
Binary Molecular Compounds
  • Always end the name in ide
  • The vowel at the end of a prefix is often dropped
    when the name of the element begins with a vowel
    (carbon monoxide not monooxide)
  • When a single atom of the FIRST element, omit the
    prefix mono-

55
Binary Molecular Compounds
  • CO2
  • 1st element one carbon, 2nd element, two
    oxygens
  • Drop the mono and name di, oxygen changes
    ending
  • to oxide
  • Carbon dioxide

56
Naming Common Acids
  • Consider acids to be combinations of anions
    connected to as many hydrogen ions (H) as needed
    to make the molecule electrically neutral
  • If the acid is a binary compound
  • hydro - root name of anion -ic acid
  • H2S hydro sulfur ic acid hydrosulfuric
    acid

57
Naming Common Acids
  • If the acid contains a polyatomic anion, omit the
    hydro -, and change an ate suffix to ic acid,
    or change an ite suffix to ous acid
  • H2SO4 sulfuric acid
  • H2SO3 sulfurous acid
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