Bonding Flashcards
Give the diagram (arrow) that shows how structure relates to bonding and bonding relates to structure
Check physical flashcards to see if you got it right
What is a chemical bond?
An attractive force holding together two or more atoms, molecules or ions
When atoms bond, what are they trying to form?
A noble gas configuration
How do elements achieve a noble gas configuration?
By sharing, loosing or gaining electrons
List the types of bonding
- Covalent bonding
- Ionic bonding
- Metallic bonding
- Dative covalent bonding
What are the two types of covalent bonding?
Simple molecular covalent bonding and giant molecular covalent bonding
What is bonded in an ionic bond?
Metals and Non-metals
What is bonded in covalent (molecular) bonding?
Two non-metals
What is bonded in metallic bonding?
Metals
Describe the bonding in ionic compounds
Ionic bonding between oppositely charged IONS
Bonding between metals ( positive charge) and non metals (negative charge)
Give examples of ionic compounds
NaCl and K2CO3
What is the structure of ionic bonds?
Giant ionic lattice
List the properties of ionic bonds? (6)
- High melting point
- Don’t conduct electricity when solid due to rigidity of IONS so they cant move
- however, they conduct electricity when molten (liquid) because IONS are free to move so they can conduct electricity
- The higher the charge, the stronger the ionic bond
- The smaller the ion, the stronger the ionic bond
They require lots of energy to overcome the force of attraction - Strong electrostatic forces of attraction between oppositely charged ions
What are you NOT expected to talk about when describing ionic bonds
- Metallic bonds
- Electronegativity
- Dipoles
- Electrons moving
List four factors that determine stronger ionic bonds
• Smaller ionic radius
Greater ionic charge, the greater charge density
• Stronger electrostatic forces of attraction between oppositely charged ions
• more exothermic (more negative) lattice enthalpy
Give another type of crystal structure
Metals
Describe the bonding between metals
Metallic bonding due to attraction between positively charged metal ions and a ‘sea’ of de localized electrons
What is the structure of metals?
Giant metallic lattice
What determines the strength of a metallic bond
•The higher the positive charge on the metal ion, the stronger the metallic bond
• Smaller the ion the higher the charge density and the stronger the metallic bond
Give the properties of metals
• High melting point
• Conduct electricity when solid
• When molten (liquid) they are good heat conductors
• Higher the charge on the ions, the stronger the bonds
Give the reasons for the properties in metals
• Strong electrostatic forces of attraction between positively charged metal ions and a sea of delocalized electrons
• A sea of delocalized electrons
Why can metals be beaten to different shapes?
They are are malleable
Give reasons for why metals are malleable
Layers of atoms can fairly easily slide over each other without breaking the bonds
List the types of intermolecular forces
• Permanent dipole dipole interaction
• Vanderwaals forces of attraction
• Hydrogen bonds
What are the elements that form hydrogen bonds
• N-H
• O-H
• F-H
What is the bond angle in water?
104.5
Which of the intermolecular forces is the weakest?
Vander waals
What is simple molecular covalent bonding?
Strong covalent bonds between the atoms, weak vander waals forces of attraction between the molecules
Are there any lone electrons in simple covalent bonding?
No - all involved in bonding
Can simple covalent molecules conduct electricity and why?
No all electrons used in bonding so they are not free to move
Do simple covalent molecular substances have a high/low mpt and bpt? Why?
Low- weak vander waals forces of attraction between molecules that do not require much energy to break
Describe macro molecular covalent bonding
Lattice in many atoms held together by strong covalent bonds
Do macromolecular substances have high mpt and bpt?
Yes - lots of energy required to overcome strong covalent bonds
Define electronegativity
The ability of an atom to attract a pair of electrons in a covalent bond
What affects electronegativity?
• Nuclear charge
• Atomic radius
• Electron shielding
What is the most electronegative element?
Fluorine, 4.0
How do you get a non polar bond
When bonding elements have the same electronegativity
What is the strongest intermolecular force?
Hydrogen bonding
How do you have a polar bond but not a polar molecule?
Different electronegativity but symmetrical
Describe vander waals forces of attraction
• Temporary dipoles created by random movement of electrons
• Induced dipole in neighboring molecule
• Temporary induced dipole attraction
Which molecules are vander waals forces stronger?
Larger molecules
Describe permanent dipole-dipole attraction
• Difference in electronegativity of elements
• Vander waals forces between molecules
• Covalent bonds between elements
Draw a molecule of water
Check physical flash cards to see if you got it right
Why is ice less dense that water?
• In liquid hydrogen bonds are constantly breaking and reforming as molecules move about
• In ice hydrogen bonds hold the molecules in a fixed position. This makes them slightly further apart in liquid water
What is a dative covalent bond/Coordinate bond? And when is it formed?
Formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion with a lone pair of electrons (not used in bonding). A covalent bond in which both electrons come from the same atom
Draw the forming of a dative covalent bond in ammonia
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Note
• Always draw out the shape when answering questions
• Covalent is sharing
• Take not of Dative/coordinate bonds
• Electrostatic
• Iodide is a bigger ion so it will have less attraction to Sodium ion
How can we determine the shape of a molecule
• Number of electrons in valence shell of atom
• Number of bonded electrons
• Total of all electrons
• Divide by number of atoms
• Number of bonded atoms
• Subtract to get lone pairs
• Shape
• Angle
What does the electron pair repulsion theory state?
• Electron pair will take up positions as far away from each other as possible, to minimize the repulsive forces between them
What is the order of electron repulsion in a substance
• LP-LP
• LP-BP
• BP- BP
List types of shapes and their angles
• Linear = 180*
• Tetrahedral = 109.5*
• Trigonal bipyramidal = 120/90
• Trigonal planar = 120*
• Octahedral = 90*
• Bent/v-shaped = 104.5*
Square planar= 90*
Note
• Read the flipping question
• Pair of electrons on - donate to -
• Strong
• To explain the shape of a molecule: Discuss pair repulsion theory and balancing of bonds attached e.g electron pairs equally repel each other
• BETWEEN THE MOLECULES
• Bigger not larger
• Be careful when deducing a similar shape
Structure of graphite
• Vander waals forces between the molecules
• strong covalent bonds within the layers
• Layers of carbon atoms
• Lots of energy required to break many covalent bonds
Which intermolecular force is the highest?
hydrogen bonding
Describe vander waals forces of attraction
- Similar electronegativity
-symmetrical molecules
-Intermolecular force
Every molecule/ compound has what?
Vander waals forces of attraction
Describe metallic bonding
• Strong electrostatic force of attraction between positively charged metal ions and a sea of delocalised electrons
• High melting point
• metallic lattice structure
• Conduct electricity when solid
• Conduct electricity when molten
Describe permanent dipole-dipole interaction bonding
• Strong covalent bonds between the atoms with different electronegativities
• Slight positive and negative charges attract opposite adjacent molecules
• Don’t conduct electricity
• More soluble in water
• Polarised
• Melting points are low but relatively higher than non-polar molecules
Which is a smaller ion, Mg2+ or Na+ and why and which will form a stronger ionic bond
• Mg2+ is a smaller ion than Na+ (ionic radius)
• Mg2+ has a higher charge density because 2+ is in a much smaller volume
• Mg2+ will form stronger ionic bonds
What is the most likely bond angle around the oxygen atom in ethanol and why?
- 104.5
- It is bonded to hydrogen and carbon which means it has two lone pairs left making the bond a bent/v-shape
hydrogen bonding is found where?
between the molecules
