Bonding Flashcards
What is a dative covalent/co-ordinate bond?
A covalent bond where the pair of electrons originates from one atom.
What two conditions are there for a dative covalent/co-ordinate bond to occur?
The atom donating the pair must have a lone pair, and the atom accepting must have a vacant orbital
What are the 3 main types of bonding?
Ionic, metallic, covalent
An arrow can be used to show a dative bond. What does the direction the arrow is pointing show?
Points from the atom donating to the atom accepting
Between what type of atoms does metallic bonding occur?
metal + metal
What does metallic bonding involve?
Attraction between delocalised electrons and positive ions arranged in a lattice
‘Electrostatic forces between positive ions and delocalised outer electrons’ describes what type of bonding?
Metallic
‘Electrostatic forces of attraction between positively and negatively charged ions’ describes what type of bonding?
Ionic
What is a covalent bond?
Where two atoms share one pair of electrons
What type of bond occurs between a non-metal + metal?
Ionic
What type of bond occurs between two non-metals?
Covalent
What is electronegativity?
The ability of an atom to attract the pair of electrons in a covalent bond
What happens to electronegativity as you go across the period?
Electronegativity would increase as atoms get bigger but similar shielding, therefore stronger nuclear charge and so stronger attraction b/w nucleus and shared pair of electrons
What happens to electronegativity as you go down a group?
As you go down a group, atom size increases and so nuclear charge does as well, but because there is increased shielding there is overall a weaker attraction (less electronegative)
A polar covalent bond occurs when_____?
One atom = more electronegative than the other
What are the 3 main types of intermolecular forces?
Van der Waal’s, dipole-dipole, hydrogen bonds
What is the strongest type of intermolecular force?
Hydrogen bonds
What affects electronegativity?
The size of the nuclear charge
The size of the atom
What is a polar covalent bond?
When one atom is more electronegative than the other
What is the difference between an induced dipole vs polar molecules?
The dipoles in polar molecules are permanent. These can attract other permanent molecules with dipole-dipole forces
Dipole-dipole bonds occur between what types of molecules?
Polar
State what is meant by a ‘hydrogen bond’
The attraction between a lone pair on a N, O, or F and the slightly positive H on a neighbouring molecule
What type of bonding occurs in NaCl and what is the resulting structure?
Ionic
Giant ionic lattice
What are the four kinds of crystal structure?
Ionic, metallic, macromolecular, molecular
What kind of crystal structure occurs in iodine?
Simple molecular
What kind of crystal structure occurs in diamond?
Giant covalent
What kind of crystal structure occurs in graphite?
Giant covalent
What kind of crystal structure occurs in ice?
Simple molecular
What kind of crystal structure occurs in magnesium?
Giant metallic lattice
Describe and explain the features of a giant ionic lattice
High melting point - oppositely charged ions held together by strong electrostatic attractions
Brittle - if a layer shifts, similarly charged ions are to close, repel and cause the structure to break open
Most can dissolve in water - +ve and -ve ions can interact with polar water molecules
Can enable a current if dissolved/melted - electrons free to move, can create flow of ions
Describe and explain the features of a simple molecular crystal
Strong covalent bonds in molecules
Weak intermolecular forces between
Low melting points
Don’t conduct - no free moving electrons
Describe and explain the features of a giant covalent diamond structure
Tetrahedral shape
Hard -v. strong covalent holding together
High mp - strong covalent
Can’t conduct - no free moving electrons
Describe and explain the features of a giant covalent graphite structure
Each C covalently bonded to 3 Cs
Soft - weak VdW between planes, so able to slide past
Can conduct across a plane but not between layers (delocalised within plane)
Describe and explain the features of a giant metallic lattice
High melting point - strong attraction between ions and delocalised electrons
Dense - same as above -pulls it close
Can conduct - delocalised electrons
Good heat conductors - same as above
Malleable - layers can slide over each other
What does VSEPR stand for?
Valence Shell Electron Pair Repulsion Theory
How many atoms are attached to a linear molecule?
2
How many atoms are attached to the central atom in a trigonal planar molecule?
3
How many atoms are attached to the central atom in a tetrahedral molecule?
4
How many atoms are attached to the central atom in a trigonal bipyramid molecule?
5
How many atoms are attached to the central atom in an octahedral molecule?
6
What are the bond angles in a linear molecule?
180
What are the bond angles in a trigonal planar molecule?
120
What are the bond angles in a tetrahedral molecule?
109.5
What are the bond angles in a trigonal bipyramid molecule?
90 and 120
What are the bond angles in an octahedral molecule?
90
A molecule has 4 pairs in total, 3 bonding and 1 lone. What is the shape of the molecule?
Trigonal pyramid
A molecule has 4 pairs in total, 2 bonding and 2 lone. What is the shape of the molecule?
V-shaped
A molecule has 5 pairs in total, 3 bonding and 2 lone. What is the shape of the molecule?
T-shaped
A molecule has 6 pairs in total, 4 bonding and 2 lone. What is the shape of the molecule?
Square planar molecule
What are the bond angles in a trigonal pyramid molecule?
107
What are the bond angles in a v-shaped molecule?
104
What are the bond angles in a T-shaped molecule?
90
What are the bond angles in a square planar molecule?
90
What are the bond angles in an octahedral based molecule?
87
