y 10 test 1 - structure and bonding Flashcards
what is the definition of an atom
the smallest particle of an element that exists
definition of molecules
two or more atoms (covalently/chemically) bonded together
Ionic bonding occurs between what type of elements
A metal and a non-metal
How are ions formed
Ions are formed by electron loss and gain to get full outer shells, so the atoms are more stable
What are ionic bonds
They are electrostatic attraction between oppositely charged ions
Why do compounds with giant ionic lattices ahve high melting/boiling points
Ions are fixed into a strong 3D lattice so it requires a lot of energy to break those bonds
Do ionic compounds conduct electricity
They don’t conduct as a solid, as the ions are fixed into position and can’t move so there are no free charge carriers
They do conduct when molter or aqueous, as the ions are no longer bonded in a fixed place, so there are free charge carriers.
How is a covalent bond formed
They are formed by atoms sharing a pair of electrons to get a full outershell
Definition of covalent bonds
Electrostatic attraction between two nuclei and a shred pair of electrons
The types of covalent bonds
single bond: 1 unpaired electron, one pair
double bond: 2 unpaired electrons, 2 pairs
triple bond: 3 unpaired electrons, 3 pairs
What elements form covalent bonds in a simple molecular structure
Non metals only
Why do simple molecular structures have low melting/boiling points
They have intermolecular forces, so it doesn’t require a lot of energy to break these bonds.
How does intermolecular forces change in simple molecular substances
As the atom gets bigger, the intermolecular forces get stronger. This is why bigger atoms have higher melting/boiling points (in general)
why do giant covalent structures have high melting/boiling points
GCS have very strong intermolecular forces, meaning they’re hard but brittle, and have high melting/boiling points
do covalent compounds conduct electricity
In general they don’t as their arent any free charge carriers. However, there are exceptions, like graphite
What is metallic bonding
Electrostatic attraction between positive ions and delocalised electrons, with metals
Properties and structure of diamond
Covalently bonded to 4 other carbons
Regular lattice arrangement
No free electrons
High melting/boiling point because of strong covalent bonds
Rigid structure makes it hard
Doesn’t conduct
Properties and structure of graphite
Hexagonal arrangement, connected to 3 other carbons
Weak forces of attraction
Soft, layers can slide over each other
Can conduct
What is an alloy
A mix of a metal and either another metal or carbon
Typical properties of metals
Solid at room temp
High melting point
Good conductors
Malleable (can be reshaped)
Ductile (can be drawn into a wire)
Strong
Dense
Why are alloys harder than pure metals
Alloys contain atoms of different, making it harder for the layers to slide over each other
