Unit 10: Covalent Compounds Flashcards
1
Q
When do covalent bonds form?
A
When atoms SHARE ELECTRONS to complete octets.
2
Q
Covalent bonds form between…
A
two non-metals (groups 4A-7A)
3
Q
What are used in the names of covalent compounds?
A
prefixes
4
Q
prefix for 1
A
mono
5
Q
mono
A
prefix for 1
6
Q
prefix for 2
A
di
7
Q
di
A
prefix for 2
8
Q
prefix for 3
A
tri
9
Q
tri
A
prefix for 3
10
Q
prefix for 4
A
tetra
11
Q
tetra
A
prefix for 4
12
Q
prefix for 5
A
penta
13
Q
penta
A
prefix for 5
14
Q
prefix for 6
A
hexa
15
Q
hexa
A
prefix for 6
16
Q
prefix for 7
A
hepta
17
Q
hepta
A
prefix for 7
18
Q
prefix for 8
A
octa
19
Q
octa
A
prefix for 8
20
Q
prefix for 9
A
nona
21
Q
nona
A
prefix for 9
22
Q
prefix for 10
A
deca
23
Q
deca
A
prefix for 10
24
Q
How to name covalent compounds:
A
STEP 1 Name the first nonmetal by its element name.
STEP 2 Name the second nonmetal with an ide ending.
STEP 3 Add PREFIXES to indicate the number (from subscripts) of atoms of each nonmetal.
25
In a hydrogen molecule (H2), each H atom... (3)
1. shares electrons to form a SINGLE COVALENT BOND
2. acquires TWO electrons.
3. becomes STABLE like helium (He).
26
What does a covalent bond indicate?
the atoms share electrons
27
In a fluorine F2 molecule, each F atom...(2)
1. shares ONE electron.
2. acquires an OCTET (8 electrons)
28
Which orbital does the bonding pair come from? (for molecules that form octets?
P orbital
29
If carbon has 4 valence electrons, how many bonds can it form?
four
30
The number of covalent bonds can be determined from...
the number of electrons needed to complete an octet
31
Steps to writing electron-dot formulas
STEP 1 Determine the arrangement of atoms.
STEP 2 Determine the total number of valence electrons.
STEP 3 Attach each bonded atom to the central atom with a pair of electrons.
STEP 4 Place remaining electrons as lone pairs to complete octets (2 for H atoms).
STEP 5 If octets are not complete, form a multiple bond by converting a lone pair to a bonding pair.
32
How many electrons are shared in a single bond?
One Pair
33
How many electrons are shared in a double bond?
Two Pairs
34
How many electrons are shared in a triple bond?
Three Pairs
35
What bond does a nitrogen molecule have?
triple
36
How to count lone pairs?
The pairs attached to the central atom that are not in a bond
37
Exceptions to the octet rule
group 3 elements, elements on the 3rd row, and beryllium and chloride
38
Why are there exceptions for group 3 elements?
they only have 3 valence electrons to bond with
39
Why are there exceptions to elements on the 3rd row?
Elements on the 3rd row have the d-orbital available to place surplus electrons
40
Why are there exceptions to beryllium and chloride?
has a small atomic radius, which makes it small enough
41
Polar molecules
molecules that contain polar bonds
42
Nonpolar molecules
molecules that contain no polar bonds or have a symmetrical arrangement of polar bonds
43
Polar bonds
Covalent Bonds with an unequal share of electrons because onr end has a higher electron density
44
Nonpolar bonds
Covalent bonds with an equal share of electrons
45
Though atoms often form compounds by sharing electrons, the electrons are not always _________
SHARED EQUALLY
46
When two atoms share electrons unequally, a ______ results.
Dipole
47
The greater the difference in electronegativity, the __________ the bond is.
More Polar
48
Electronegativity difference for nonpolar
0-0.4
49
Electronegativity difference for polar
0.5-1.9
50
Electronegativity difference for ionic
2.0-4.0
51
Are polar molecules symmetrical or asymmetrical?
asymmetrical
52
Are nonpolar molecules symmetrical or asymmetrical?
symmetrical
53
Polar molecules must contain...
polar bonds
54
How can polar bonds be determined?
through differences in electronegativity of atoms
55
Symmetrical Molecules have...
polar bonds that cancel each other out
56
Examples of symmetrical molecules
Linear (more than 2 atoms), Tetrahedral, Trigonal Planar
57
Examples of Asymmetrical molecules
Bent and Linear w/ 2 Atoms
58
What forces form between ionic compounds?
electrostatic interactions
59
What forces form between covalent compounds?
dipole-dipole, hydrogen bonds, (London) dispersion forces
60
Electrostatic interactions are the ______ forces
strongest
61
Dispersion forces are the ________ forces
weakest
62
Dipole-dipole attractions
interaction between +ve end of one molecule and a -ve end of another
63
Hydrogen Bond forms when
Hydrogen atoms in one molecule are attracted to the atoms F, O, or N in another molecule.
64
Dispersion forces are...
Weak attractions between nonpolar molecules and caused by the MOVEMENT OF ELECTRONS
65
Dipole Moment
a measure of the separation of positive and negative charges within a system, or its overall polarity
(magnitude 1 x distance between atoms)
66
