3. Bonding Flashcards
How do ions in ionic compounds achieve stability?
Their electron configuration is the same as a noble gas after they have gained/lost an electron
What is an ionic bond?
The electrostatic force of attraction between the two oppositely charged ions
Will ionic bonds exist in isolation?
No, they will always form part of a giant ionic lattice
When two ions are more charged, what will this mean for the forces of attraction between them?
The more charged the ions are, the greater force of attraction between them
Are ionic compounds ever molecules?
No
What does the formula ‘NaCl’ represent?
That there is a one to one ratio of sodium to chloride ions
What is the formula for an ammonium ion?
NH4+
What is the formula for a chlorate ion?
ClO3-
What is the formula for a cyanide ion?
CN-
What is the formula for a carbonate ion?
CO3 2-
What is the formula for a chromate ion?
CrO4 2-
What is the formula for a dichromate ion?
Cr2O7 2-
What is the formula for a hydrogen carbonate ion?
HCO3 -
What is the formula for a hydrogen phosphate ion?
HPO4 2-
What is the formula for a hydrogen sulfate ion?
HSO4 -
What is the formula for a hydroxide ion?
OH-
What is the formula for a nitrate ion?
NO3 -
What is the formula for a nitrite ion?
NO2-
What is the formula for a manganate ion?
MnO4-
What is the formula for a peroxide ion?
O2 2-
What is the formula for a phosphate ion?
PO4 3-
What is the formula for a sulfate ion?
SO4 2-
What is the formula for a sulfite ion?
SO3 2-
What is the formula for a thiosulfate ion?
S2O3 2-
What is a covalent bond?
A shared pair of electrons, where each electron come from a different atom
What happens when a pair of electrons is shared?
A single bond is formed
How is a double or triple covalent bond formed?
If two or three pairs of electrons are shared
What type of covalent bond does a H2 molecule have?
Single covalent, H-H
What type of covalent bond does an O2 molecule have?
Double covalent, O=O
What type of covalent bond does an N2 molecule have?
Triple covalent, N≡N
What is a coordinate bond?
When both electrons come from the same atom
What is a coordinate bond also known as?
A dative covalent bond
What are ammonium ions formed from?
NH3 and H+
How is an ammonium ion formed?
- NH3 molecule has a lone pair of electrons, and H+ ion has no electrons
- the lone pair in NH3 donates electrons to vacant orbital in the hydrogen (COORDINATE BOND FORMED)
How is a coordinate bond represented in displayed formula?
As an arrow, showing where electrons have been donated
What are the types of covalent bonding?
- simple molecular
* giant covalent (macromolecular)
Where does metallic bonding exist?
Within a metal, as there is no bonding between metals
Why do electrons in metallic bonding become delocalised?
There are no non-metal atoms to transfer electrons to
What does the number of delocalised electrons in metallic bonding depend on?
The number of outer electrons the metal atom has
What happens in metallic bonding when there are more delocalised electrons?
Increased attracted between ions and electrons as ions more strongly charged
What is a metallic bond?
In a metal, when positive metal ions and delocalised electrons attract each other and hold the structure together
Do metallic bonds exist in isolation?
No - they form part of a giant metallic lattice
What is the strength of ionic, covalent and metallic bonds?
Very strong
What are the four types of crystal structure?
- ionic
- metallic
- macromolecular (giant covalent)
- (simple) molecular
Why can ionic compounds dissolve in water?
Positive ions in lattice are attracted to opposite charged atom in water and vice versa (as water is a polar molecule)
Why can ionic compounds conduct electricity and heat when molten or in aqueous solutions?
Positive and negative ions are free to move and therefore carry charge
Why do ionic compounds have high melting points?
Lots of electrostatic forces of attraction between positive and negatively charged ions, which take a lot of energy to break
Why are ionic compounds brittle?
If it is bent then layers slide over each other so that like charges are next to each other, then repel and break apart
Why don’t simple covalent compounds conduct electricity or heat?
There are no free charged particles to carry charge - only ends of molecules are slightly charged so they are neutral
Why do simple covalent compounds have low melting points?
There are weak intermolecular forces between molecules which need little energy to break
Why don’t giant covalent compounds conduct electricity? Is there an exception to this?
No charged particles that are free to move
graphite conducts - 1 free electron per atom
Why do giant covalent compounds have high melting points?
Lots of strong covalent bonds which take a lot of energy to overcome
Why are giant covalent compounds not soluble in water?
No charged particles - all carbon are neutral so don’t attract to H2O molecules
Why do metals conduct electricity and heat?
Have delocalised electrons that can carry a charge
Why do metals have high melting points?
Electrostatic forces - ‘metallic bonds’ - need a lot of energy to be broken
Why are metals malleable and ductile?
Layers of ions can slide past each other easily - bonds flexible although strong
What substances are typical of monatomic structures?
Elements: group 0
What substances are typical of simple molecular structures?
- Elements: H₂, O₂, N₂, F₂, Cl₂, Br₂, I₂, At₂, S₈, P₄
* Compounds: different non-metals bonded
What substances are typical of giant covalent structures?
- Elements: Silicon, carbon (diamond and graphite)
* Compounds: SiO₂
What is the structure in monatomic substances?
Individual atoms with very weak forces between them
What substances are typical of ionic structures?
Compounds: metal and non-metal bonded
What substances are typical of metallic structures?
Elements: one metal
What is the structure in simple molecular substances?
Individual molecules with weak forces between them
atoms within molecules are joined by covalent bonds
What is the structure in giant covalent substances?
Lattice structure in which all atoms are joined to other atoms by covalent bonds
What is the structure in ionic substances?
Lattice structure of +ve and -vely charged ions
held together by ionic bonds
What is the structure in metallic substances?
Lattice structure of metal ions with outer shell electrons free to move through the structure
What are the particles in monatomic substances?
Atoms
What are the particles in simple molecular substances?
Molecules
What are the particles in giant covalent substances?
Atoms
What are the particles in ionic substances?
Ions
What are the particles in metallic substances?
Ions and delocalised electrons
What is the formula for monatomic substances?
Just the symbol e.g. Ar
from periodic table
What is the formula for simple molecular substances?
Need to learn common examples e.g. H₂O, CO₂, CH₄
What is the formula for giant covalent substances?
- Elements: just the symbol
* Compounds: ratio of atoms e.g. SiO₂, C, Si (need to learn common examples)
What is the formula for ionic substances?
Need to learn common ions and work out formula
e.g. MgCl₂ - ratio of Mg:Cl ions is 1:2
What is the formula for metallic substances?
Just the symbol e.g. Fe
from periodic table
What is the type of structure and bonding in sodium chloride?
Ionic
What are the particles present in sodium chloride?
Ions - Na+ and Cl-
Explanation of bonding in sodium chloride?
+vely charged Na ions attracted to -vely charged Cl ions to create ionic bond
Explanation for melting/boiling point of sodium chloride?
High - strong ionic bonds take a lot of energy to overcome
Explanation for conductivity of sodium chloride?
Conducts when molten or dissolved in water - ions need to be free to move
Why is sodium chloride brittle?
When shifted, ions will be next to same charged ion and repel naturally
What is the type of structure and bonding in magnesium?
Giant metallic lattice of Mg ions - metallic bonding within the metal
What particles are present in magnesium?
Ions and delocalised electrons
Explanation of bonding in magnesium?
Attraction between +vely charged ions and -vely charged electrons - electrostatic forces of attraction
Explanation for melting/boiling point of magnesium?
High - electrostatic forces of attraction take a lot of energy to overcome
Explanation for conductivity of magnesium?
Can conduct as delocalised electrons can move and carry a charge
What is the type of structure and bonding in diamond?
Macromolecular - carbon atoms
What are the particles present in diamond?
Carbon atoms
Explanation of bonding in diamond?
Each carbon atom is bonded to four other carbon atoms covalently
Explanation for melting/boiling point of diamond?
High - many strong covalent bonds - lots of energy to break - and no intermolecular forces
Explanation for conductivity of diamond?
Doesn’t conduct - neutral as not charged, and no free electons - no moving particles
(however good thermal conductor)
What is the type of structure and bonding in graphite?
Macromolecular - giant covalent structure
What are the particles present in graphite?
Atoms
Explanation of bonding in graphite?
- each carbon atom joined to three others covalently
- carbon atoms form layers with a hexagonal arrangement (layers have weak forces in between)
- each atom has one non-bonded, delocalised electron
Explanation for melting/boiling point of graphite?
High - covalent bonds
Explanation for conductivity of graphite?
Conducts - delocalised electron per atom is free to move