Bonding & Structure Flashcards
Name the 4 types of solids
Ionic, Metallic, covalent, Molecular
Ionic bonding is between…
metal cations & non-metal anions
Covalent bonding is between…
Non-metal atoms
Molecular bonding is between…
non-metal atoms & molecules
Metallic bonding is between…
Metal atoms
What solids cannot conduct electricity?
Ionic (but can conduct electricity when dissolved in water), molecular, covalent 1D chains and 3D networks
Why can these solids conduct electricity?
Some solids can conduct electricity due to delocalized (freely moving) electrons
Why can solids not conduct electricity?
No charged particles or freely moving electrons
Describe Ionic bonding
There is a strong electrostatic attraction between metal cations & non-metal anions to form a giant 3D lattice
Describe covalent bonding
There is a large network of atoms covalently bonded in linear 1D chains, 2D layers & 3D networks
Describe metallic bonding
The metal atoms are bonded to all other metal atoms in a 3D lattice
Describe intermolecular forces (molecular)
There are weak forces & attractions between molecules
Describe intreamolecular forces (molecular)
There are strong covalent bonds between atoms in each molecule
What types of solids are soluble?
Ionic, Molecular (only polar molecules)
What types of solids are insoluble?
Metallic, Molecular (only non-polar molecules), Covalent
Describe & explain 3D network (covalent)
Include conductivity, MP/BP, hardness
The non-metal atoms in a 3D network are held in strong & rigid structures
There are no charged particles, so it cannot conduct electricity
They have a high MP/BP due to the strong covalent bonds
Describe & explain 2D layers (covalent)
Include conductivity, MP/BP, hardness
They have a high MP/BP due to the strong covalent bonds
It can conduct electricity, as there are freely moving electrons
These layers slide over each other without disrupting the bonds; making them slippery
Describe & explain 1D chain (covalent)
Include conductivity, MP/BP, hardness
It cannot conduct electricity as there are no charged particles or freely moving electrons
Long 1D chains have more sites available for intermolecular forces; so they have a high MP/BP
These chains can slide over each other making them soft & flexible
Describe & explain molecular solid
Include conductivity, MP/BP, hardness
There are weak intermolecular forces holding the molecules together; which means this has a low MP/BP. Due to this weak force and attraction, the molecules can easily separate which makes them soft.
They cannot conduct electricity as there are no charged particles.
Molecules can be polar or non-polar. Polar molecules are soluble in water and non-polar molecules are insoluble in water
Describe & explain ionic
Include conductivity, MP/BP, hardness
Ionic solids are held together by strong electrostatic attractions in a 3D lattice; which requires lots of energy to break so there is a high MP/BP
Ionic bonds are brittle, when pressure is applied, ions move and like charges repel causing the lattice to break.
They cannot conduct electricity as the ions cannot move from their fixed position, however, when melted, ions are free to move allowing them to conduct electricity
Ionic solids are soluble, as the ions are separated due to attraction towards the polar water molecules
Describe & explain metallic
Include conductivity, MP/BP, hardness
Metal atoms are held together in a 3D lattice by metallic bonding. There is a strong attraction between + metal atoms & electrons. The electrons are freely moving, hence they are able to conduct electricity.
Metals are not soluble in water, as the metallic bonds are to strong to be broken.
Many metals are hard & strong & therefore have a high MP/BP.
Metals are malleable and ductile as the layers of atoms are able to slide over each other without disputing the bonds
What is the bond angle of a tetrahedral arrangement
109.5
What is the bond angle of bent/V-shaped
109.5 (if tetrahedral arrangement)
120
What is the bond angle of trigonal planar
120
What is the bond angle of linear shape
180
What is the bond angle of trigonal pyramid
109.5
What is the most Electronegative atom
F
What does EN stand for
Electronegativity
How do you show the Electronegativity of an atom
Dipole arrows
How do you identify if a molecule is polar
It contains polar bonds
It is asymmetrical, so dipole arrows are unable to cancel out
How do you identify if a molecule is non-polar
It contains polar bonds
It is symmetrical, so dipole arrows cancel out
Describe endothermic
Endothermic is the energy absorbed from the surroundings.
Bond breaking is endothermic
Describe exothermic
Exothermic is the energy released to the surroundings.
Bond making is exothermic
What is Ea
Activation energy- minimum energy required for a reaction to take place
Solid –> powder –> gas
is this endo or exo?
Endothermic reaction as it is bond breaking
Gas –> powder –> solid
is this endo or exo?
Exothermic reaction as it is bond making
What calculation is required to calculate moles
n = m / M
When drawing Lewis structures, what atom is always in the middle
C
If the sign of the enthalpy change is negative, what reaction is it
Exothermic reaction
If the sign of the enthalpy change is positive, what reaction is it
Endothermic reaction
What calculation is used when calculating bond enthalpy change
bonds broken - bonds formed
In an exothermic reaction are there more products than reactants, or more reactants than products
More reactants than products
In an endothermic reaction are there more products than reactants, or more reactants than products
More products than reactants
What are the exceptions to the octet rule
H, He, Li = 2 e- max Be = 4 e- max B = 6 e- max P = 10 e- max S = 12 e- max
If a molecule is polar & the dipoles are unable to cancel out, what does this mean
There are lone pairs; the molecule is asymmetrical
Describe & explain if BF3 is polar or non-polar
BF3 molecule has 3 B-F covalent bonds. The B-F covalent bonds are polar due to the difference in electronegativity between B & F, with F being more electronegative than B. Thus B-F bonds form dipoles: B (delta positive) & F (delta negative). These dipoles are arranged in a trigonal planar shape and so are arranged symmetrically around the central atom. These dipoles are able to cancel out, so the molecule is a non-polar molecule overall
Describe & explain if NH3 is polar or non-polar
NH3 molecule has 3 covalent bonds. The N-H covalent bonds are polar due to the difference in electronegativity between N & H, with N being more EN than H. Thus N-H bonds form dipoles; N (delta negative) & H (delta positive). Due to the lone pair of electrons, these dipoles are arranged in a trigonal pyramid shape and so are arranged asymmetrically. These dipoles are unable to cancel out, so the molecule is a polar molecule overall
Describe & explain the shape of SO2
SO2 molecule, there are 3 electron clouds around the central atom S. These regions repel as far apart as possible due to the valence electron pair repulsion into a trigonal planar arrangement, resulting in a bond angle of 120. There are 2 regions of electrons that are bonding and 1 region of an electron that are lone pairs, which are not observed, so the shape of the molecule is bent/V-shaped
