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Unit 5 Chemistry Exam

Terms in this set (62)

How are electrons arranged in ionic compounds and in covalent (molecular compounds)
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Assign charge to ions
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Write and name compounds
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What are the three basic types of bonds
1. Ionic bond -"losing or gaining" Attractive forces between ions. Exist in ionic compound. If it loses an electron the other electron would gain and then this would form an ionic bond.
2. Covalent bond-electrons are shared. Exist in molecules, or covalent compounds.
3. Metallic bond-exist in metals. Due to the outermost electron and they will move in the electrical current.
Valence electrons
Electrons on the outermost energy level of an atom. For A groups.
Lewis symbol
the representation of an atom that shows valence electrons as dots around the symbol of the element
Cation
positively charged ion (lost electrons)
Anion
negatively charged ion (gained electrons)
Ionic Symbol
Chemical abbreviation + charge. Ex: Cl2+
losing electrons
takes less energy than gaining electrons
Group 1A,2A,3A
it will lose an electron making it a positive charge called a cation
Group 4a
Share electrons most of the time.
5A,6A,7A,8A
It will gain an electron making it a negative charge called anion
8A
noble gases"do not react"
Hydrogen
can carry 1+or 1-
Isoelectronic species
Carry equal amount of electrons. See how many electrons are there and see if they are equal.
For ex: Na+ because it is in group 1A it will lose that electron. You calculate the number of electrons and subtract the # it is losing in this case 11-1=10
Ex: Mg 12-2=10e
O=8+2=10e
F=9+1=10e
These four would be considered isoelectronic species.
Metals form
positive ions (cations)
Non metals form
negative ions (anions)
metal+nonmetal form
covalent compound also called molecular compound. Typically share electrons.
cross down rule
1. Write down the ion.
2. Cross over
Ex: Mg+2.N-3-=
( Mg3N2. Erase charges and just leave like that
Ex:Mg+2 O-2
=Mg2 O2. Since they are the same divide by 2 and you will get MgO
Metallic atoms form
positive ions (cations)
Nonmetal atoms
form negative ions (anions)
Polyatomic ions form
Ionic compounds. For example: NH4+ Cl-
If it formed only by nonmetals we suspect it to be
covalent compound=share electrons.
Cl2
Is a molecule. The atoms share electrons.
Compound
more than one element.
Molecular geometry
Reactivity
Linear
B-A-C
bent
Trigonal Planar
Trigonal pyramid
Tetrahedral
Molecules with 2 VSEPR GROUPS
It is linear
Electronegativity
left to right it increases
bottom to top it increases
Atomic size =Atomic radii
Decreases as one goes from left to right at the same period, increases from top to bottom in the same group.
Periods indicate how many
shells
so period 1 has 1 shell
period 2 has 2 shells
and so on.
when the attraction increases
the size of the atom gets smaller. The electrons will be closer to the nucleus.
IUPAC rules
1. Distinguish between ionic compound and covalent compound
Ionic will most likely contain metals.
Compound will most likely contain non metals.
Distinguish between fixed charge metal and variable charge metal
Fixed metals: 1A 2A 3A and ZN,AG,CD.
Variable charge metals: All B groups except (ZN,AG,CD)
Memorize
1. Copper (I) =
2. Copper (II)=
3. Iron(II)=
4. Iron(III)=
1. Copper (I) =Cuprous
2. Copper (II)= Cupric
3. Iron(II)=Ferrous
4.Iron(III)=Ferric
memorize polyatomic ions
Binary ( compound)
means there are two different elements.
Ex: CO2
Prefixes
mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
Examples
CO2=CARBON DIOXIDE
N2O5=Dinitrogen pentoxide
PCL5=phosphorus pentoxide
Ionic bond
Is the
electrostatic attraction between ions,
in ionic compounds
, after losing or gaining
electrons among atoms.
Covalent bond
Is the
sharing of
electrons
among atoms
Metallic bond
Is formed by outmost
electrons of one metal atom
wander around many metal
atoms.
Valence electron No. of an A group
element = ?
ts group no.
Elements (from A groups, main groups) in the same group have
the same valence electrons (except He)
true
An ion
after losing or gaining electron(s), an atom becomes an
ion
An ion
after gaining electrons, the atom becomes a negatively
charged ion. The number as the superscript is the number of
electrons gained
An cation
after losing electrons, the atom becomes a positively
charge ion. The number as the superscript is the number of
electrons lost
What is the central concept behind VSEPR?
electron pairs repel each other to be as far as possible from each other. After reaching a balance, it forms a shape
Electron Domains
Electron Domains are also called electron groups, but not electron pairs!!


Each electron pair is an electron domain.

•A double or triple bond, is counted as one electron domain
Molecules with three VSEPR electron groups
Three groups, without electron pairs, is trigonal planar

Three groups, with one electron pair, is bent
...
Four groups, without electron pairs, is tetrahedral

Four groups, with one electron pair, is trigonal pyramidal

Four groups, with two electron pairs, is bent
electronegativity increases as you go
from left to right across a row.
...from the bottom to the top of a column
Binary ionic compound
: An ionic compound that contains exactly
two different
elements
. CaBr2, MgO, NaCl, etc
fixed charge
Fixed charge: one element has only one kind of charge
Na+
Ca2+
Al 3+
Group I, II, IIIA metals have fixed charges
variable charge
one element has more than one kind of charge
Transitional metals (metals in B
groups) tend to have variable charges.
(exception: Zn and Ag, which means,
Zn and Ag are not variable charge
metals)
ternary compound
a compound composed of three elements
1. Which of the following statements concerning double covalent bonds is
correct
?
D) They always involve the sharing of 2 electron pa
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