Unit 2 - Bonding Structure And Properties Of Matter Flashcards
What are made when electrons are transferred
Ions
What groups are most likely to form ions
1,2,6,7
What structure if an ionic compound
Regular lattice structure
Properties of ionic compound
High metlting and boiling points, strong bonds , can’t conduct electricity, ions separate free to move, carry electrical current
What do covalent bonds usually have
Simple molecular structure
Properties of covalent bond
String covalent bonds, weak intermolecular force, melting boiling points low, don’t conduct electricity, no free electrons or ions
What are polymers
Lots of small units are linked together to form a long molecule. All atoms are joined by strong covalent bonds
Name some giant covalent structures
Diamond, graphite, Graphene
Properties of diamond
-Giant covalent structure
-4 covalent bonds
-really hard (lot of energy to break)
- high melting point
-don’t conduct electricity
-No free electrons
Properties of graphite
3 covalent bonds
Sheets of carbon in arranged in hexagons
Held together weakly
High melting point
Conducts electricity
1 delocalised electron
Soft and slippery
Properties of Graphene
One layer of graphite
Joined in hexagons
Very strong
Contains delocalised electrons so can conduct electricity
Properties of metals
Solid at room temp
Good conductors of heat and electricity
Malleable
What are nanoparticles
Really really tiny, have a large surface to volume ratio
Uses of nanoparticles
Can be used in electric circuits
Can be added to polymer fibres to make surgical masks and deodorants
Used in cosmetics for example to improve moisturisers
Why must magnesium chloride by molten or dissolved in water to be electrolysed
-so ions can move to the electrodes
-and ions carry charge
How is magnesium produced at the negative cathode
-magnesium ions attracted to the electrode
-magnesium ions gain 2 electrons (reduced)
Explain why metals can be bent or shaped
Layers of particles can slide easily
Limitations of models for ionic compounds: dot and cross diagram
Doesn’t indicate the relative sizes of the atoms, doesn’t illustrate the 3D arrangements of the atoms and electron shells
Limitations of models for ionic compounds: 3D construction models
It is not to scale, gives no information about the forces of attraction between the ions or movement of electrons
Limitations of models for ionic compounds: 2D representations of ionic compounds
Does not show where the ions are located on the other layers
In terms of electrons what helps you tell the melting boiling point of a metal
The greater the number of outer electrons that the metal has, the higher its melting/boiling point.
Why is it that the greater the number of outer electrons that the metal has, the higher its melting/boiling point
This is due to the increased positive charge on the metal ion and the increased number of electrons that are delocalised, resulting in stronger bonding
Describe metallic bonding in terms of electrons
-The electron in the outer shell of every atom is delocalised (free to move) so there is a sea of delocalised electrons
-Strong electrostatic attraction
What is an alloy
Mixture of metals
Limitations of the particle model
Many particles are not spherical, particles are no solid
Why can’t ionic compounds conduct electricity
Their ions are held in fixed positions and cannot move
What is the arrangement of atoms in pure metals
The atoms are arranged in neat layers
Describe how atoms are arranged in an alloy
The smaller or bigger atoms distort the layers of atoms in pure metals
What can Graphene be used in real life
Electronics and composites
Diameter of a nano particle
Between 100 and 2500 nm
Nano particles uses in real life
Medicine, electronics and sun cream
Advantages of nano particles
Can be used as cosmetics as it is absorbed much deeper into the skin
Can be used to deliver medicines as readily absorbed
Disadvantages of nano particles
Breathing in tiny particles could have a negative effect on our lungs
Might damage our cells as easily absorbed
Could accumulate in organisms over time
What is meant by a weak acid
The acid is only partially ionised in aqueous solution
Describe how metals conduct electricity
-metals have a delocalised electrons
-the electrons carry electrical charge
-the electrons move through the structure
why do alloys not conduct electricity as well as pure metals
-in alloys different sized atoms distort the layers
-so the movement of the delocalised electron is different
Describe what happens when a magnesium atom reacts with an oxygen atom
Magnesium loses electrons
Oxygen gains electrons
Two electrons are transferred
Magnesium and oxygen ions are formed
What is the structure and bonding of diamond
-giant structure
-with covalent bonds
-and four bonds per carbon atom.
Why does diamond have a high melting point
-strong covalent bonds
-and many covalent bonds must be broken
-so a lot of energy required to break the bonds
What forces hold together ions with opposite charges?
Electrostatic
Why does sodium oxide have a huge melting point
-giant structure
-with strong electrostatic forces of attraction between ions
-so large amounts of energy required to break the bonds
Explain why an ionic compound can conduct electricity when molten
Ions are not free to move in solid lattice
But are to to move when it is molten
What is the shape of a buckminsterfullerene molecule
Spherical
One use of a fullerene
Catalysts, drug delivery
Why would a liquid have a low boiling point
Weak intermolecular forces
Why is graphite soft and slippery
No covalent bonds between layers
So layers can slide over each other
So graphite is soft and slippery
Observations of potassium in water
-floats
-moves around
-fizzing
Why does the reactivity of elements change as you go down group 1
-Reactivity increases as you go down group 1
-because the outer shell is further from the nucleus
-so there is more shielding from the nucleus
-so the atom loses an electron more easily
Which elements are often used as a catalyst
Transition metals
Why is it important to use a reaction with a high atom economy
Less waste
why calcium reacts more vigorously than magnesium with hydrochloric acid of the same concentration
calcium has a greater number of electrons shells than magnesium, this means the distance between the positive nucleus and negative electrons is greater, making the force between them weaker. This means that it requires less energy for the calcium atoms to lose its 2 electrons in its outer shell compared to magnesium.
