Elements and Compounds

1
Elements and Compounds
2
Elements

• Can not be broken down by chemical means
• Chemical alphabet
• Building blocks
• First 92, 88 occur in nature
• w/ exception of plutonium, above 92, they are
  synthesized

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Atom

• Smallest unit of an element that retains the
  characteristics of that element
• Smallest unit of an element that can enter into a
  chemical reaction
• Contain sub-particles

4
Distribution of Elements
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Rules for Element Symbols

• Symbols have one or two letters
• If one letter, capitalize it
• If two, only capitalize the first

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Periodic Table

• Increasing atomic number
• Left to right
• Mendeleev
• Similar chemical properties in families

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Metals and Nonmetals

• Metals

• Nonmetals

• Solid at room temp (except Hg)
• Lustrous
• Good conductors
• Malleable
• Ductile
• High melting point
• High density
• Dont commonly combine with other metals but when
  they do, they form alloys
• Commonly combine with nonmetals to form minerals,
  chlorides, oxides and sulfides

• Not lustrous
• Poor conductors
• Low melting points
• Low densities
• Can be solid liquid or gas
• Form molecular compounds when combined with each
  other

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Metalloids

• Boron, silicon, geranium, arsenic antimony,
  tellurium and polonium
• Properties of both metals and nonmetals

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Diatomics

• H2
• N2
• O2
• F2
• Cl2
• Br2
• I2

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Compound

• Substance containing two or more elements
• Can be broken down
• Atoms of the elements in a compound are combined
  in whole number ratios
• Molecular and ionic compounds

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Compounds

• Molecular

• Ionic

• Smallest uncharged individual unit of a compound
  formed by the union of two or more atoms
• water

• Positively or negatively charged group of atoms
  or atom
• Held together by the attractive forces between
  ions or groups of ions
• Ions are negatively (anion) or positively
  (cation) charged
• Sodium chloride

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Chemical Formulas

• Abbreviations
• Shows symbols and abbreviations of atoms of
  elements in compound
• Subscripts are used to indicate numbers of atoms
  of elements present in compound
• Subscripts are the small numbers partially below
  H2O
• 2 hydrogen atoms, 1 oxygen atom