Chemical Bonding ☹️ Flashcards
Which is smaller - mass number or atomic number?
Atomic number
Define isotopes
Atoms of the same element with same number of protons but different number of neutrons
What properties do isotopes of the same element have
They are the same as they have the same amount of electrons
How do ionic compounds bond
By losing or gaining electrons to make a full shell
( draw the one with square brackets )
What ions do metals generally form and what are they called?
+ve ions
Cations
What ions do non-metals generally form and what are they called?
-ve ions
Anions
How are +ve and -ve ions held together?
Strongly, by electrostatic forces of attraction in a giant lattice
Why do ionic substances have high melting and boiling points?
Strong electrostatic forces of attraction between oppositely charged ions throughout giant structure require lots of heat energy to break
Why are ionic substances hard but brittle?
Strong forces of electrostatic attraction, but layers can slide, and when ions of same charge align, the structure breaks
Why are ionic substances generally soluble in water?
Ions are attracted to polar water molecules, and this attraction breaks the lattice apart
Why do ionic substances NOT conduct electricity in solid state?
Charged ions are held in position and are not free to move
Why do ionic substances conduct electricity when liquid (or dissolved in solution)
The charged ions are free to move
How do covalent compounds bind?
They share a pair of electrons by donating electrons to the shared pair
They then have the same structure as noble gases
Covalent bonds are sometimes also called molecular bonds
What are the two types of covalent?
Simple molecular
Giant covalent
What are simple molecular?
Made up of tiny molecules which contain multiple atoms held together by covalent bonds
What are giant covalent?
They contain millions of atoms bonded together by MANY strong covalent bonds to form a giant molecule, or macromolecule
E.g graphite and diamond
Fun fact cos I can’t think of a question for this
Covalent bonds can share two or three electron pairs too
Why do simple covalent substances have low melting and boiling points?
Because there are only weak intermolecular forces between molecules, these only need little heat energy to overcome
Why do simple covalent substances have poor electrical conductivity?
There are no charged ions or free electrons present
Why are simple molecular substances poorly soluble in water?
There are no charged particles present to be attracted to polar water molecules
How do you draw a dot and cross diagram for covalent substances
Like a Venn diagram yk
Why can giant covalent substances have such different properties?
Because each atom can be bonded to a different amount of other atoms
Diamond - bonded to 4 others
Graphite - bonded to 3 others
But both are carbon
What is the structure of diamond?
Each carbon atom covalently bonded to 4 others
Why is the melting point of diamond so high?
MANY strong covalent bonds require lots of heat energy to break
Why is diamond so hard?
Very hard due to MANY strong covalent bonds
Why is diamond a poor electrical conductor?
There are no free electrons, as they are all used in bonding
Describe the structure of graphite
Each carbon atom is covalently bonded to 3 others
Graphite has a layered structure with weak intermolecular forces between layers
Why does graphite have a high melting point?
Because strong covalent bonds within layers require lots of heat energy to break
Why is graphite so soft?
Layers can easily slide over each other due to weak intermolecular forces
Why is graphite a good electrical conductor?
There are free electrons between layers (delocalised electrons)
What are metallic bonds?
Bonds in metals idfk boo
Why do metallic bonds have high melting and boiling points?
Strong attractions between positive metal ion and sea of delocalised electrons
Why are metals malleable and ductile?
Layers of metal ions can slide over each other, so structure doesn’t shatter
Why are metals good electrical conductors?
Lots of free delocalised electrons that can move around structure
Why are metals good conductors of heat?
Delocalised electrons gain kinetic energy, so move faster and transfer energy throughout the metal
What is graphene?
A single layer of graphite
Strongest known substance
Could be used for lightweight construction materials
First discovered fullerene?
Buckminsterfullerene (C⁶⁰)
What are fullerenes?
3D hollow shapes made of carbon
Low mps and bps
Can deliver drugs, act as lubricants and as catalysts
What are carbon nanotubes and their uses?
- strong cylindrical fullerenes that are good conductors of heat and electricity
- catalysts often attached to it as they have a large SA
What are polymers?
Long chain molecules
Strong intramolecular forces, weak intermolecular forces, but solid at room temp
What is polythene?
A type of polymer used for plastic due to its weaker intermolecular forces making it more flexible
