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valence electrons
electrons in the atom's outermost energy level
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family # tells what about valence electrons?
how many are available
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What is directly related to the number of valence electrons?
reactivity
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which groups have the most reactive elements?
groups 1 and 17
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octet rule
in forming compounds atoms tend to gain or lose electrons to achieve the electron configuration of a noble gas
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Who defined the octet rule? why?
Gilbert Lewis; to explain why noble gases are unreactive.
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metals ______ valence electrons; nonmetals ______ valence electrons.
lose; gain
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electron dot structure
diagrams that show electrons as dots around an element's symbol
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atom
electrically nuetral because it has equal numbers of protons and electrons
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ions
form when an atom or groups of atoms loses or gains electrons
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cation; charge?
is formed when anatom or group of atoms loses valence electrons; postive; more protons than electrons.
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naming cations
- metallic elements- the name of the ion is the same as the name of the element
- -ex: sodium atom from the sodium cation (Na+)
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anion
atom or group of atoms with a negative charge
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formation of anions
gain of electrons by a nuetral atom or groups of atoms
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naming anions
name of an anion of a non-metal is NOT the same as the neutral atom; take the root of the atom name and add suffix -ide
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when group 7A(17) elements form ions we call them ______ ion.
halide
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ions of transition metals
- -charges may vary
- -some of the ions formed by transition elements do NOT have an octet configuration.
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Formation of an ionic bond
- compounds composed of cations and anions
- -usually composed of metal cations and nonmetal anions
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ionic compounds are _______ ________.
electrically neutral
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how do you find the total negative charge of anions?
the total positive charge of the cations is equaled by the total negative charge of the anions
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ionic bond
electrostatic forces that hold ions together
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what must be specified if cations have more than one oxidation state?
oxidation state
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traditional naming
- does not indicate actual charge.
- ending in "ous": lower oxidation #
- ending in "ic": higher oxidation #
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stock system
- actual charge.
- Fe+2= Iron (II)
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chemical formulas
shows the kinds and numbers of atoms in the smallest representative unit of a substance
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formula units
the lowest whole-number ratio of ions in an ionic compound
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oxidation numbers
equivalent to the charge of the ions
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most ionic compounds are what at room temperature?
solids that form crystals
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properties of ionic compounds
high MP, brittle, not malleable or ductile, can conduct electricity when melted or dissolved
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coordination number
the number of ions of opposite charge that surround an ion in a crystal
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metallic bonds
results from the attraction of the free floating valence electrons for the positively charged metal ions
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metals are made up of..
closely packed cations rather than neutral atoms
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valence electrons of metal atoms are modeled as what?
- sea of electrons
- -valence electrons are mobile
- -they can drift freely from one part of the metal to another
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sea of electrons explains many prop. of metals:
- conductivity- electricity is made up of electrons
- -as 1 electron enters the cloud at 1 end another leaves at the other end
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prop. of metals
mealleability and ductility- cations slide past eachother and electrons flow around in response to the force applied
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crystalline structure of metals: 3 possible arrangements
body centered, face-centered cubic, hexagonal close packed
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body centered
- every atom except on the surface has 8 neighbors
- ex. Na, K, Fe, Cr, W
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face-centered cubic
- every atom has 12 neighbors except surface atoms
- ex. Cu, Ag, Au, Al, Pb
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Hexagonal close packed
- every atom has 12 neighbors like face centered but are arranged differently
- ex. Mg, Zn, Cd
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Metal alloys
- brass- alloy of copper and sinc
- -corrosion resistance,increased ductility or hardness, stronger (compared to metals)
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alloy
mixtures of 2 or more elements at least one of which is a metal
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substitutional alloy
atoms ofthe alloy components are similar, can replace eachother in the crystal form. EX. bronze
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interstitial alloy
- atoms of the alloy components are very different in size.
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