Bonding Flashcards
What type of bonding exists between metals and non-metals
Ionic bonding
What happens to electrons in ionic bonding
They are transferred from metal to non-metal
Describe the nature of an ionic bond
The electrostatic attraction between oppositely charged ions
Describe the structure of ionic compounds
Giant ionic lattice of positive and negative ions held together by electrostatic forces
Explain the melting point of ionic compounds
High melting point because strong electrostatic forces within ionic lattice which require a great deal of energy to break
Explain the electrical conductivity of ionic compounds
Conduct when molten or dissolved because ions can move but do not conduct as a solid because ions held in fixed position in lattice
Which would you expect to have a higher melting point, NaCl or MgO and why
MgO because ions are double the charge of NaCl so stronger electrostatic forces
What is the formula of the ionic compound Aluminium Sulfate
Al2(SO4)3
What happens to electrons in covalent bonding
Electrons are shared between non-metal atoms
What is the difference between a single and double covalent bond
Single is 2 shared electrons in bond, double is 4 shared electrons
Describe the bonding in diamond
Each carbon is bonded to 4 other carbons in a tetrahedral shape
Describe the structure of graphite
Layers of carbon atoms arranged in hexagonal pattern with weak bonds and delocalised electrons between layers
Explain why graphite conducts electricity
Delocalised electrons are free to move and carry charge
Explain the hardness of diamond
Atoms are held in fixed positions
What is a co-ordinate (dative) bond
Where one atom contributes both electrons in a covalent bond
Give an example of a molecule with co-ordinate bonding
NH4+, AlCl3NH3, CO
Why do molecules have different shapes?
Electron pairs repel each other as far apart as possible.
Which has the greater repulsion effect lone pair of electrons or a covalent bond?
Lone pair
What is the bond angle in a linear molecule?
180°
What is the bond angle in a trigonal planer molecule?
120°
What is the bond angle in a tetrahedral molecule ?
109.5°
What shape molecule has 6 bonding electron pairs eg SF6, and what is the bond angle
Octahedral, 90 degrees
What shape molecule has 5 bonding pairs eg. PCl5 and what are the bond angles
Trigonal bipyramidal, 90 degrees and 120 degrees
What is the shape and bond angle of CH4. Why
Tetrahedral, 109.5 degree, electron pairs repel each other as far as possible
How do lone pairs affect bond angles
Reduce bonding pair bond angles (by approx. 2 degrees per lone pair) as they repel more than bonding pairs
What is the shape and bond angle in water. Why
Bent, 104.5 degree, 4 pairs of electrons including 2 lone pairs
What is the shape and bond angle in ammonia. Why
Trigonal Pyramidal, 107. degree, 4 pairs of electrons including 1 lone pair
What is the shape and bond angle in SiCl62- Why
Octahedral, 90. degree, 6 bonding pairs of electrons 0 lone pairs
Why is the is the bond angle in water less than 180°?
Water contains two bonds and two lone pairs. Lone pairs repel further than bonded pairs of electrons.
Where in the periodic table are the most electronegative elements
Top right (not including noble gases)
Which is the most electronegative element
Fluorine
Which of these bonds will have a dipole? H-C or Cl-C
Cl-C
What causes molecule to be polar (2 requirements)
significant differences in electronegativity and asymmetrical shape
Why is CCl₄ not a polar molecule?
Symmetrical molecule so dipoles cancel out.
Define electronegativity
The ability of an atom to attract electron density (the electron pair) in a covalent bond
What causes bond polarity
Differences in electronegativity between two atoms bonded together
Name the 3 types of intermolecular force in order from weakest to strongest
Van der Waals, dipole-dipole and hydrogen bonding
Which type of intermolecular force exists between diatomic molecules
Van der waals only
Which types of intermolecular force exist in carbon dioxide
Dipole dipole forces
Explain how Van der Waals forces arise
Temporary dipoles because of movement of electrons which induce temporary dipoles in neighbouring molecules
Explain how dipole dipole forces arise
Partial positive charge attracting partial negative charge
Explain why the boiling point of alkanes increase with increasing chain length
More Van der Waals forces
Describe the structure of iodine
Molecular lattice of I2 molecules held tougher by Van der Waals forces
What 3 elements could be bonded to hydrogen to give hydrogen bonding
Oxygen, nitrogen or fluorine
What is a hydrogen bond?
an electrostatic attraction between a proton in one molecule and an electronegative atom in the other.
How does hydrogen bonding affect boiling point
Increases boiling point
Describe the structure of ice
Regular lattice structure of water molecules held together by hydrogen bonding. Less dense than water
Describe the strucutre of metals
Giant metallic lattice of positive metal ions surrounded by delocalised electrons
Explain why Mg has a higher melting point than Na
Doubly charged metal ion
Explain why metals conduct electricity
Delocalised electrons are free to move and carry charge
Explain why metals have high melting points
The delocalised electrons are strongly attracted to the positive metal ions (strong metallic bonds) which requires a lot of energy to overcome
