C2 - Structure and Bonding (mine) Flashcards
What are the three common states of matter?
solid, liquid, gas
What are the properties of solids?
extremely hard to compress, as there are almost no spaces between the particles
fixed shape, can not flow from place to place
What are the properties of liquids?
extremely hard to compress, because the particles are close together with not many spaces between them
take the shape of their container, the particles flow over each other
what are the properties of gases?
extremely easy to compress, because the particles are widely spaced
gases spread out and fill the space or their container, because the particles in a gas move quickly and randomly
How can we change the state of a substance?
By putting in or taking out energy
solid -> liquid
melting
energy is put in
liquid -> gas
boiling
energy is put in
gas -> liquid
condensing
taking away energy
liquid -> solid
freezing
taking away energy
solid -> gas
sublimation
energy is put in
gas -> solid
deposition or desublimation
energy taken way
Where does melting take place at?
the melting point
where does freezing take place at?
the melting point
where does boiling take place at?
the boiling point
where does condensing take place at?
the boiling point
Why do some materials have a higher melting point that others?
Different materials have different forces of attraction that holds the particles together, these forces needs to be broken to melt the substance
higher forces of attraction between the particles, leads to greater energy need to break them, so there is a higher melting point.
What are the limitations of the simple particle molecule?
It assumes that all particles are solid spheres, which is not true
It assumes that there are no forces between the particles
Elements react in order to …
achieve a full outer energy level
Ionic bonding is when …
a metal reacts with a non-metal
During ionic bonding ..
the outer-shell electrons
pass from one element
to the other element
so both atoms achieve a full outer-energy level
What do ionic compounds form?
giant ionic lattices
explain the structure of giant ionic lattices
giant ionic lattices has positive ions surrounded by negative ions
Explain the attraction in giant ionic lattices
Giant ionic lattices have very strong electrostatic forces of attraction between the positive and the negative ions
What are the properties of ionic compounds (giant ionic lattices)
High melting and boiling points
Conducts electricity only when they are melted or dissolved in water, not when they are solids
why do giant ionic lattices have high melting and boiling points?
the electrostatic forces between the positive and negative ions require a lot of thermal energy to break, as they are very strong
why do giant ionic lattices only conduct electricity when they’re melted or dissolved in water, but not as solids?
As solids, in giant ionic lattices, the ions cannot move, they’re locked in place by the strong electrostatic forces, so they cannot act as charge carriers
When the ionic compounds are melted or dissolved in water, the ions can now move and can carry the charge
Covalent bonding is when …
a non-metal reacts with a non-metal
During covalent bonding …
the electrons are shared between atoms in pairs
1 shared pair of electrons are known as …
a single covalent bond
2 shared pairs of electrons are known as …
a double covalent bond
Explain the structure of small covalent molecules (simple molecular substances)
the molecular substances are held together by weak intermolecular forces, however the molecules themselves are held together by strong covalent bonds
what are the properties of small covalent molecules?
They have low melting and boiling points, meaning that they are usually gases or liquids at room temperature
they do not conduct electricity
why do simple molecular substances have low melting and boiling points?
Despite, the strong covalent bonds within the molecules, between the molecules there are weak intermolecular forces. The intermolecular forces take very little energy to break. So not a lot of thermal energy is need to melt or boil the substance - it will have a low melting and boing point.
Why do small covalent molecules not conduct electricity?
They have no charge carriers to carry current. The molecules do not have an overall electric charge.
As the size of small covalent molecules increase ..
(in terms of melting and boiling point)
so does the melting and boiling points as there is more intermolecular forces that need to be broken, so more energy is needed
Why are giant covalent structures always solids at room temperature?
giant covalent structures have millions of strong covalent bonds (and no weak intermolecular forces).
describe the structure of giant covalent structures
many strong covalent bonds but no weak intermolecular forces
what element is diamond formed from?
carbon
Describe the structure of diamond?
Each carbon atom forms four strong covalent bonds.
This leads to an overall tetrahedral shape.
What are the properties of diamond?
Diamond has a very high melting and boiling point
Diamond does not conduct electricity
Why does diamond have a high melting and boiling point?
Diamond has a huge number of very strong covalent bonds (each carbon atom forms 4), these bonds take a large amount of energy to overcome, in order for the substance to be melted.
Why doesn’t diamond conduct electricity?
Since each carbon atom is bonded with four other carbon atoms, it leaves no electron to be delocalised, there are no free electrons to carry electrical charge.