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Atoms and ions
Atoms
have no charge
Ions
Charged atoms
Cations ( + charged)
Anions ( - charged)
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Atomic number and atomic mass
Atomic number (Z) Number of protons = number of
electrons
Z = p+ = e-
Atomic mass (A)
Number of protons + number ofneutrons
A = p+ + no
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COMPLETE THE TABLE:SYMBOL Z A p+ e- no
Na 11 12
Fe 26 30
Rb+1
85 37
S-2 16 16
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Metalloids
Zigzag line dividing metals andnonmetals
Have properties of bothmetals and nonmetals
They are very goodsemiconductors (component
of microchips in electronics)
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Metalloids
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CHEMICAL FORMULAS Consists of the symbols of the elements
accompanied by subscripts to the right of the
symbols
Ex. H2C12H22O11
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CHEMICAL FORMULAS
Subscripts
tells the number ofatoms of the element on the left
C12H22O11
12 carbon; 22 hydrogen; 11oxygen atoms
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Rules for Writing Formulas
3. Write the symbol
for the MOREMETALLIC ELEMENT
first.
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Metallic propertyDECREASING METALLIC PROPERTY
INCREASING
METALLICPROP
ERTY
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EXAMPLE
SO2
Sulfur, the more
metallic element, iswritten first.
Oxygen is written last
since it is less metallic
There are 2 atoms for
oxygen, thus a subscript
of 2 is written after the
symbol
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Naming Binary Compounds
Binary compounds
Made up of two elements
Ionic compounds
Contains a metal + nonmetal
Covalent compounds
Contains two nonmetals
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Ionic compounds (metal + nonmetal)
Examples:
Na and Cl NaCl
Mg and S MgS
Rule:
Name the metal (Na is Sodium)
Name the nonmetal ending in
ide(Cl is
Chlorine + -ide= chloride)
NaCl is Sodium choride
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Ionic compounds (metal + nonmetal)
Examples:
Mg and O2 MgO2
Rule:
Name the metal (Mg is Magnesium)
Name the nonmetal ending in ide(O2
is
Oxygen + -ide= oxide)
MgS is Magnesium oxide
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Answer:
1.KI
2.CaBr2
3.Al2O3
4.Li3N5.Na2O
1.Potassium iodide
2.Calcium bromide
3.Aluminum oxide
4.Lithium nitride5.Sodium oxide
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Covalent Compounds
(nonmetal + nonmetal)
Examples:
C and O2 CO2
Si and C SiC Steps:
1. Name the elements in the order that
they appear in the formula
2. Drop the last syllables (or two/three) in
the final element and add ide.
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Covalent Compounds
(nonmetal + nonmetal)
Step 3.
Add prefixes to
the name ofeach element
to indicate the
number ofatoms.
PREFIX NUMBER
Mono- 1
Di- 2
Tri- 3
Tetra- 4
Penta- 5
Hexa- 6
Hepta- 7
Octa- 8
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CO2 is Carbon dioxide
carbon
CO2Oxygen + -ide isoxide Two indicates
the suffix Di-
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SiC is Silicon monocarbide
Silicon
SiCCarbon + -ide iscarbide No subscripts
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Exercise: Name the following
1.CSe2
2.SF6
3.CS2
4.CCl45.S4N2
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Answer:
1.CSe2
2.SF6
3.CS2
4.CCl45.S4N2
1. Carbon diselenide
2. Sulfur hexafluoride
3. Carbon disulfide
4. Carbon tetrachloride
5. Tetrasulfur dinitride