Chemical Bonding Flashcards
(135 cards)
1
Q
_____do not have tendency to lose or gain electrons among the elements
A
Carbon
2
Q
Electments that have smaller number of electrons in their outershell are____ and are the _____
A
Cations
Metals
3
Q
Electments that have larger number of electrons in their outershell are____ and are the _____
A
Anions
Non-metals
4
Q
Lead in group 4,what kind of cation will it form?
A
Pb2+ instead of Pb4+
Also Sn in gp 4 can form both Sn2+ and Sn4+
Silver form Ag+
Hydrogen can form H+ and H-
5
Q
What are polyatomic ions?
A
Polyatomic-contains more than one atom
Ions-charged molecules
6
Q
What is ionic bond?
A
Attractive force b/w metal ion and nonmetal ion formed by complete transfer of electrons from metal to nonmetals
7
Q
What is covalent bond?
A
Attractive force b/w nonmetals and nonmetals formed by sharing of electrons
8
Q
What is metallic bond?
A
Attractive bond b/w metals and its delocalized electrons.
9
Q
Octet rule
A
the tendency of atoms to gain stable outer sheel with 8 electrons
10
Q
Bond length
A
The distance b/w the nuclei of two bonded atoms
11
Q
Bond strength or bond enthlpy
A
The energy required to break the bond
12
Q
How bond length and bond strength relate?
A
Inversely proportional
(Bond lengthတိုလေstrengthပိုများလေ—energyပိုလိုလေ)
13
Q
Cations
A
Metal ions formed by loss of electrons
14
Q
Anions
A
Nonmetal ions formed by gain of electrons
15
Q
What is the bond length along Gp 7?
A
down the gp atomic size increases then bond length increases therefore bond strength decreases
16
Q
Compare bond length b/w single bond,double bond and triple bond
A
Single bond>Double bond>Triple bond
17
Q
Compare bond length b/w single bond,double bond and triple bond
A
Single bond<Double bond<Triple bond
18
Q
Which has longest bond length;single bond,duble bond or triple bond?
A
Single bond
19
Q
Which has shortest bond length;single bond,duble bond or triple bond?
A
Triple bond
20
Q
Which has strongest bond strength;single bond,duble bond or triple bond?
A
Triple bond
21
Q
Which has weakest bond length;single bond,duble bond or triple bond?
A
Single bond
22
Q
2 types of chemical bonding
A
1)Intramolecular bond
2)Intermolecular bond
23
Q
What is intramolecular bond?
A
Bond between the atoms within one molecule
24
Q
What is intermolecular bonds?
A
Bond between molecules
25
Which is more stronger; intermolecular or intramolecular?
Intramolecular bonds are more stronger
26
Types of intramolecular bonds
1)Ionic bond
2)Covalent bond
3)Metallic bond
27
Types of intermolecular bonds
1) Van der Waals Force a.London dispersion force
b.Dipole-dipole force
c.Dipole induced dipole force
2)Hydrogen bond
28
Ionic bond is formed due to the ______ b/w oppsitely charged ions.
Electrostatic force
29
Ionic compund
Compound formed by ionic bond
Eg.NaCl,MgO
30
Ionic compound have ____ structure.
3D crystalline lattice structure
31
Coordination number of lattice structure
Number of ions that surrond the ions in the lattice.
eg.NaCl coordination number=6
32
NaCl coordination number=6
Each Na+ ions is surrounded by 6 Cl- ions and each Cl- ions is surrounded by 6 Na+ ions.
33
Lattice energy
Strength of attraction b/w ions within the lattice structure (The energy released when ions are bound to formed lattice structure)
34
Properties of ionic compound
1) Solid
2) Volatile low or non volatile
3) High boiling point and melting point
4) Brittle
5) Conduct electricity in molten state
6) Souble in polar solvents
35
NaCl and MgCl2 which have higher boiling point? Why?
MgCl2 b/c it has greater ions charge of 2+
36
Ionic compound are soluble in both polar and non polar solvents.True or False?
False
Only soluble in polar solvents
37
Ionic coumpound can conduct electricity? True or False
Not conduct electricity in solid state but can conduct when in aquesous state
38
Forces b/w covalent bonding
1) Repulsion force b/w bonded nuclei
2) Electrostatic attraction force b/w shared pair and nuclei
39
Double bond is formed___
when 2 pairs of electrons are shared.
40
Triple bond is formed____-
when 3 pairs of electrons are shared.
41
Types of covalent bond based on polarity
1) Polar covalent bond
2) Non polar covalent bond
3) Pure covalent bond
42
Electronegativity of Hydrogen
2.2
43
Electronegativity of Lithium
1.0
44
Electronegativity of Sodium
0.9
45
Electronegativity of Berylium
1.4
46
Electronegativity of Boron
2.0
47
Electronegativity of Carbon
2.6
48
Electronegativity of Nitrogen
3.0
49
Electronegativity of Oxygen
3.4
50
Electronegativity of Fluorine
4.0
51
Electronegativity of Magnesium
1.3
52
Electronegativity of Aluminium
1.6
53
Electronegativity of Silicon
1.9
54
Electronegativity of Phosphorus
2.2
55
Electronegativity of Sulphur
2.6
56
Electronegativity of Chlorine
3.2
57
Periodic trend of electronegativity
Decrease down the group
Increase across the period
58
What is the electronegativity difference if compound is pure covalent compound?
0
59
What is the electronegativity difference if compound is non polar covalent compound?
0-0.4
60
What is the electronegativity difference if compound is polar covalent compound?
0.5-1.8
61
What is the electronegativity difference if compound is Ionic compound?
>1.8
62
How electrons was shared if electronegativity b/w them is 0?
Equal share of electrons
63
How electrons was shared if electronegativity b/w them is 0-0.4?
Nearly equally shared
64
How electrons was shared if electronegativity b/w them is 0.5-1.8?
electrons are unequally shared (spend more time near more electronegative atoms and forming delta ends)
65
How electrons was shared if electronegativity b/w them is 1.8?
Complete Transfer of electrons
66
Electronegativity of Bromine
3.0
67
What elements have highest electronegativity?
Fluorine (4.0)
68
Properties of covalent bond
1) Gases or liquids
2) High volitility
3) Low melting point & boiling point
4) Non-conductor (no delocalized electrons)
5) Polar covalents are soluble in polar solvents
Non polar covalents soluble in non polar solvents
69
Dative bond or coordinate bond
Type of covalent bond in which both electrons in shared pair come from one atom.
Eg.CO
70
What is incomplete octet?
The covalent molecule that have tendency to accept an electron pair from a molecule with a lone pair.
Eg.BF3, BeCl2
71
What is expanded octet?
Atoms (Period 3 and beyond) can have more than 8 electrons because of d orbitals
Eg.PCl5, SF6
72
Odd electron molecules
Molecules with odd number of total electrons
eg.NO,NO2
73
Which molecules deviate from octet rule?
1) Incomplete octet
2) Expanded octet
3) Odd electron molecules
74
Strengthe of metallic bond is determined by_____
Number of delocalized electrons
Charge of cations
Radius of cations
75
The more the number of delocalized electron, the stronger the metallic bond is.True or False?
True
76
The greater the charge on cations the stronger the bond is.True or False?
True
77
The greater the radius of cations the stronger the bond is.True or False?
False
78
Properties of metallic compounds
1) Good electric and thermal conductivity
2) Melliable
3) Ductile
4) High melting point
5) Shiny apperance
6) solid (except mercury)
79
Are alloys compounds?
No
They are homogenous mixture not a compound.
80
What are alloys?
Metals made by adding one metal to another in molten state.
More stable,more resistant to corrosion
81
Brass
Alloy of copper and zinc
82
Bronze
Alloy of copper and tin
83
All of the metallic compound are solid.True or False?
False
Except mercury (liquid at room temperature)
84
metallic compound are soluble in both polar and nonpolar solvents.True or False
False
They are insoluble in both.
85
Are ionic compounds charged after the electron transfer? What must be done to make sure that the resulted compounds are not charged?
No
one atom’s electrons transferred to another to complete octet rule. No net loss or gain of electrons——> electrically neutral
86
Ioni compound form ______ structure.
Lattice structure
87
Ionic compounds have ——— melting and boiling points. Explain
High
The forces of attraction between ions are strong and require a lot of energy to break. The greater the charges on the ions, the stronger the force of attraction and the greater the melting and boiling points
88
Boiling points of ionic compounds is higher than that of water. T or F
True.
Sodium chloride boiling points —>800 Water boiling points - 100
89
Ionic compounds have —— volatility
Low volatility or non volatile
Our everyday encounter with them as crystalline solids with low odour is consistent with this.
90
Ionic compound sodium chloride dissolves in water but not in oil. Why?
Like dissolves like
Water——> polar compound, the partial charges in water molecules are attracted to ions of opposite charge in the lattice, which may cause ions to dislodge from their position
Oil——> non polar, no opposite attractions to separate the charged atoms in the lattice====> insoluble
91
Why cant ionic compounds conduct electricity in solid state?
The electrical conductivity depends on whether it contains ions that are able to move and carry a charge .
Ionic compounds in the solid state, cannot move and are held firmly within the lattice and so cannot move.
However, in the liquid, the ions can flow freely and thus conduct electricity
92
What kind of elements in the periodic table is most reactive combination for ionic compounds ? Think from the point of views of metal and non-metal components
Me:tal- the tendency to lose electrons increases down the group Eg Li Na K Ru Cs
Eg Li Na K Ru Cs
Non metals - the tendency to gain electrons decreases down the group. Bcuz smaller atoms——> more nuclear attraction as they are nearer to the nucleus
Eg F Cl Br I
So the highest tendency to react together and form ionic compounds will be between metals on the bottom left and non- metals on the top right of the Periodic Table
93
The electronegativity difference of ——— will give you ionic compounds
1.8 or more
94
AlCL3 is ——— bond
Covalent bond
Although Al is metal and chlorine is non-metal, electronegativity difference between Al and Cl doesnt exceed 1.8 and above. Therefore , they form covalent bond.
But AlF3 is ionic bond
95
MnI has —— bond
Ionic bond. Although their electronegativity difference is less than 1.8——> they are still claimed as ionic bonds
Metals + non-metals====> ionic bonds AlCL3 and BeCl2 is an exception
96
There are 78 percent of nitrogen in the atmosphere . Why cant organisms use it?
N2 triple bonds——> very hard to break to use
97
A single covalent bond share ——- electrons
A double covalent bond share ——— electrons A triple covalent bond share ——— electrons
2
4
6
98
The ——- bonds are stronger bonds according to bond strength
Shorter
Thinking from periodic table, the atomic radius increases down the group , so the longer bonds are expected
The bigger in size——> the weaker the force of attraction , so bond enthalpy ( the energy required to break the bonds) decreases as they are
easier to break
99
Polar bonds form because of ———-
Unequal sharing of electrons bcuz of electronegativity difference. The more electronegative an atom, the stronger it attracts electrons
100
What does dipole mean?
The term dipole is often used to indicate the fact that this type of bond has two separated opposite electric charges. The more electronegative atom with the greater share of the electrons, has
become partially negative or 𝛅–, and the less electronegative atom has become partially positive or 𝛅+.
101
How do microwaves heat food?
Microwave- low energy , high wavelength absorbed by polar covalent bonds, notable water, fat and also sugar. The absorption causes water to heat up and cook the food, leading the oven surface and containers of glass, plastic or ceramic unaffected
102
C-H bond has no polarity
False. Although they are largely non polar, there is still electronegativity difference between two atoms——->so a bit polarity exists. Except diatomic molecules such as F2, Cl2 and I2——> all the other molecules have polarity
103
Ionic bonds and covalent bonds, which is stronger?
Ionic single bonds are held together by electrostatic force of attraction. Which is much stronger than vander waal forces of shared pair of electrons in the covalent single bond
Therefore, ionic bonds are stronger than covalent bonds. Generally. But covalent triple bonds may have stronger strength compared to ionic bonds sometimes
104
What is a dative bond?
A coordinate bond in which a shared pair of electron comes entirely from an atom. An arrow head is sometimes used to show a coordinate bond, indicating the origin of electrons
105
VSEPR changes the molecular structure of a compound when there is ———
Lone pairs of electrons present
106
Electron domains means ———
All the electrons locations present in the valence shell, including single bond, double bond, triple bond and lone pairs
107
Why does the presence of lone pairs, change the bond angles of the molecules ?
Non-bonding pairs (lone pairs) have a higher concentration of charge than a
bonding pair because they are not shared between two atoms, and so cause slightly more repulsion than bonding pairs. The repulsion decreases in the following order:
lone pair–lone pair > lone pair–bonding pair > bonding pair– bonding pair
108
Electron domain geometry is the same as ———— when there is no lone pairs present
Molecular geometry
109
Dipole dipole interaction is the ——— force
Intermolecular force b/w the opposite charges of the polar molecules
110
How can bond orders of resonance structure be calculated?
Bond order= the number of bonds / number of domains
111
The stronger the bond order———> the stronger the ———
Attraction
Decreasing the bond length
112
Giant molecular cystalline solids made from Covalent bonding
Eg, diamond , graphite
Made of carbon , infinite covalent Bondings within a single molecule with a repeating unit of covalent bonds
113
London dispersion force
non-polar molecules such as chlorine , since the electrons are moving around, electron densities are constantly changing and sometimes, the electron densities happen to be greater over one region of a molecule than over the other region ——> temporary or instantaneous dipoles, when that happens , it also induces instantaneous dipoles in the neighboring atoms. That attraction is called London dispersion forces , very weak. Low melting point . As no much energy is needed for breaking the weakest bond
114
London dispersion forces increases with ————
Increasing molecular size as more electrons——> more possibilities to form London dispersion force
115
Cl2, Br2, I2, and F2 which have higher melting points?
I>Br>Cl>F
Bcuz increasing number of electrons——-> more London dispersion forces and higher boiling and melting points
116
CH4 C2H6 C3H8 C4H10 which have highest melting points
C4H10 more molecules——> more electrons more London dispersion forces
117
London dispersion forces are present only in non polar molecules. T or F
False. Polar molecules also have. But ignored bcuz of stronger forces present
118
Dipole- dipole attraction are present in
Covalent compounds with unequal sharing of electrons
Dipole-dipole forces are stronger than London-dispersion forces and considerably have higher melting points than non-polar molecules with the same masses
119
Hydrogen bondings occur in the compounds with ———
Hydrogen and high electronegative atoms such as fluorine, oxygen and nitrogen
120
List the intermolecular forces from strongest to weakest
Hydrogen bonding- strongest Dipole dipole- strong
London dispersion forces - weak
121
Compare the boiling points of two isomers of C2H60
Alcohol
Form hydrogen bonds.
Ether
R-O-R’ no hydrogen bonds
So alcohol has a higher melting point
122
Liquid water and ice which have higher density?
Water
Normally——> molecules contract when cold.
But in water, due to the presence of hydrogen bondings, water expands when cooled. So ice is maximally hydrogen bonded in the structure, with tetrahedral shape holding the molecule at a distant apart
123
When the covalent molecules boil or melts, ——— bond break
Intermolecular bondings break not the covalent and ionic bondings. When u boil a water kettle, u break the hydrogen bonds between them u don’t get H and oxygen atoms
124
Which molecule has the highest hydrogen bonding?
HF NH3 and H20
HF
So why does H2O have higher boiling points? Bcuz H20 has 2 hydrogen bonds and HF has one
But still HF has higher boiling points than HF. The bpt of molecules need to be considered in the strength of the hydrogen bonds being formed+ the number so
125
Non polar solvents are able to dissolve non polar substances due to ———
Dipole dipole interaction among them
126
Ethanol is soluble in water whereas heptanol is not. Why?
The solubility of polar compounds is, however, reduced in larger molecules where the polar bond is only a small part of the total structure. The non-polar parts of the molecule, unable to associate with water, reduce its solubility. For example, while ethanol (C2H5OH) is readily soluble in water, the larger alcohol heptanol (C7H15OH) is not. The difference is the size of the non- polar hydrocarbon group.
127
Giant molecular structures have —— solubility in all solvents
Poor
Giant molecular substances are generally insoluble in all solvents, as too much energy would be required to break the strong covalent bonds in their structure. Beaches made primarily of sand, SiO2, do not dissolve when the tide comes in and a diamond ring can safely be immersed in water.
128
Covalent compounds are volatile
True
Non polar covalent compounds are the highest Chlorine—> volatile
129
Are all covalent compounds not capable of electrical conductivity?
No. Giant compounds can, eg graphite and graphene
130
What is metallic bonding?
In the elemental state, metals’ electrons become delocalized and wander around through the metal struture. The force of attraction between the lattice of cations and the delocalized electrons . This is known as metallic bonding
131
Transition metals have ——— melting points High ? Low?
High due to a large namer of electrons that can become delocalized from both d and s subshells
132
What are steel, bronze, brass and stainless steel mixed of?
Steel- carbon + other elements
Stainless steel-chromium+ iron + nickel
Brass-copper+zinc
Bronze-copper+tin
133
Ozone is —— molecule
Polar
134
Pi bonds are —— than sigma bonds because
Weaker.
Pi bonds are weaker than sigma bonds as their electron density is further from the positive charge of the nucleus, and so they break more easily during chemical reactions
135
How can carbon form 4 bonds?
C - 1s2 2s2 2px1 2py1 ===> when bonding —->excited sate 1s2 2s1 2py1 2pz1
C* excited state
electron configuration
4 singly occupied orbitals are available for bond
