Chapter 3

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Chapter 3 Classification of Matter

• Elements Distribution, Names, Symbols
• Elements - Metals, Nonmetals, Metalloids
• Diatomic Molecules
• Chemical Formulas
• Mixtures

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Elements

• Element A substance that cannot be decomposed
  into simpler substances by chemical means.

• Make up our chemical alphabet.
• Over 100 known elements

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Elements

• Element Our building block of all substances.
• Numbered in order of increasing complexity

• Elements through 92 are known to occur in nature.
  with 4 exception Technetium (43), Promethium
  (61), Astatine (85), Francium (87)
• Above 92 only Plutonium (94) occur in nature.
• Above 92 all elements must be synthesized in the
  laboratories in small quantities

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Elements

• Most substances can be decomposed into two or
  more simpler substance.
• Water Hydrogen and Oxygen
• Sugar Carbon, Hydrogen, and Oxygen
• Salt Sodium and Chloride

5
Elements

• The smallest particle of an element that can
  exist is an atom,
• which is also the smallest unit of an element
  that can enter into a chemical reaction.
• Atoms are made up of subatomic particles that
  will be discussed later in the semester.

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Distribution of Elements

• Elements are distributed unequally in nature
• Ten elements make up 99 of the mass of the
  Earths Crust, seawater, and atmosphere
• Oxygen is about 50 of this mass
• Two elements are liquids at room temperature
• Bromine and Mercury
• Eleven elements are gases
• Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine,
  Helium, Neon, Argon, Krypton, Xenon, and Radon
• All other elements are solids

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Distribution of Elements

• Elements are distributed unequally in nature
• Figure a, shows the distribution in the glalaxies
• Figure b, shows the distribution in Earths crust
• Figure c, shows the distribution in Humans

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Sources of Element Names
Greek-Color

• Iodine from the Greek iodes meaning violet.

Latin- Property

• Fluorine from the Latin fluere meaning to flow.
  The fluorine containing ore fluorospar is low
  melting.

German- Color

• Bismuth from the German weisse mass which
  means white mass.

Location

• Germanium discovered in 1866 by a German chemist.

Famous- Scientists

• Einsteinium named for Albert Einstein.

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Symbols of the Elements

• Each element has an abbreviation.
• Iodine is taken from Greek work iodes, meaning
  violet.
• Bismuth is from German, weisse masse, white mass.
• Germanium is due to its discovery by a German
• Others are named in commemoration of famous
  scientist

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Symbols of the Elements

• Each element has an abbreviation Symbols
• Some (14) have single letter
• The rest have 2 letters
• The symbol stands for the element itself
• For one atom of the element
• For a particular quantity of the element
• Rules.
• Symbols have either one or two letters
• If one letter Capitalized
• If two letters First letter capitalized
  second letter lower case

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Rules governing symbols of the elements are

1. Symbols have either one or two letters.

1. If one letter is used it is capitalized.

H hydrogen
C carbon
Ne neon

1. If two letters are used, only the first is
   capitalized.

Ba barium
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Symbols of the Elements

• Symbols and names are on the inside cover.
• Possibly make flash cards to learn these symbols.

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Metal, Nonmetals, and Metalloids
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Metal, Nonmetals, and MetalloidsMetals

• Most of the elements are metals
• Solids at RT (except mercury)
• Malleable Can be hammered or rolled into
  sheets.
• Ductile Can be Drawn into wires
• High Melting point
• High density
• Combine with non-metals to form ionic compounds
• Often found as alloys Homogenous mixtures

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Metal, Nonmetals, and Metalloids

• A few of the less reactive metals such as copper,
  silver and gold are found in the free state.
• Metals can mix with each other to form alloys.
• Brass is a mixture of copper and zinc.
• Bronze is a mixture of copper and tin.
• Steel is a mixture of carbon and iron.

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Metal, Nonmetals, and Metalloids

• Nonmetals
• Low melting points and density
• Generally poor conductors of heat and
  conductivity
• Combine with one another to form molecular
  compounds
• Metalloids
• Properties are intermediate between metals and
  nonmetals
• Some are raw material for semiconductor

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Metalloids

• boron
• silicon
• germanium
• arsenic
• antimony
• tellurium
• polonium

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• Compounds

• Compound A substance with a constant
  composition that can be broken down into elements
  by chemical processes.
• Atoms in a compound are always
• whole number ratios
• Two types - molecular and ionic

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Compounds

• Molecule The smallest uncharged individual unit
  of a compound formed from 2 or more atoms
• Ion Positively or negatively charged atom or
  group of atoms.
• Held together by attractive forces from
  positively and negatively charged ions
• Cation Positively charged
• Anion Negatively charged

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Compounds can be classified as molecular or
ionic. Ionic compounds are held together by
attractive forces between their positive and
negative charges. Molecular compounds are held
together by covalent bonds.
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Diatomic Molecules

• Special type of molecule
• Contain 2 atoms alike or different
• Seven elements are diatomic molecules
• Hydrogen - H2
• Oxygen - O2
• Nitrogen - N2
• Fluorine - F2
• Chlorine - Cl2
• Bromine - Br2
• Iodine - I2
• Need to know these!!!!

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Occurrence of Diatomic Molecules
Hydrogen H Not found in nature.
Hydrogen H2 Found in nature.
Nitrogen N Not found in nature.
Nitrogen N2 Found in nature.
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Chemical Formulas

• Used as abbreviations for compounds
• Shows the symbols and the ratio of the elements
  in a compound
• H2O
• Indicates 2 Hydrogens and one Oxygen
• H2SO4
• Indicates 2 Hydrogens, 1 Sulfur, and 4 Oxygen

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• Water has the formula H2O.

• It does not contain free hydrogen, H2 or free
  oxygen, O2.
• The H2 part of H2O means that 2 atoms of hydrogen
  are combined with one atom of oxygen in the water
  molecule.

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chemical formulas
Serve as abbreviations of the names of compounds.
CaCl2
calcium chloride
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chemical formulas
Tell which elements the compound is composed of
and how many atoms of each element are present in
a formula unit.
CaCl2
calcium chlorine
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chemical formulas
Show the symbols of the atoms of the elements
present in a compound.
CaCl2
Ca calcium Cl chlorine
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chemical formulas
Show the ratio of the atoms of the elements
present in a compound.
CaCl2
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Chemical Formulas

• Formula of a compound contains the symbols of all
  the elements
• Formula contains one atom of an element the
  number 1 subscript is left out
• Formula contains more than one atom of the same
  element the number is indicated as a subscript
  written to the right of the symbol of that atom
• When a formula contains more than one group of
  atoms occur as a unit a parentheses is place
  around the group with the number subscripted
• Ca(NO3)2

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Chemical Formulas
H3PO4
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Chemical Formulas
Ba3(PO4)2
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Chemical Formulas

• Formulas written as H2O, H2SO4, Ca(NO3)2 and
  C12H22O11 show only the number and kind of each
  atom contained in the compound they do not show
  the arrangements of the atoms in the compound or
  how they are chemically bonded to each other.

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Concepts - Chapter 3

• Classify elements, compounds, mixtures
• Write symbols or name for common elements
• Understand chemical formulas
• Differentiate between atoms, molecules, ions
• Know some characteristics of metals, nonmetals
  and metalloids
• Recognize elements that occur as diatomic
  molecules