Topic 1- Key Concepts Flashcards
1
Q
State symbols
A
Ag - Aqueous
l - liquid
g - gas
s - solid
2
Q
Ionic equations
A
- Show the part of the formula that is reacting
- State symbols are included
3
Q
History of the atom
A
- Early 18th century,John Dalton described atoms as solid spheres
- JJ Thompson - Plum Pudding
- Rutherford - Gold leaf
- Bohr - Fixed orbits
4
Q
Componentof the atom
A
- Proton - Positiviley charged, mass of 1, in the neucleus
- Neutron - no charge, mass of 1, in the nucleus
- Electron - Negativley charged, mass of 0.00005, orbiting the neucleus
- Nucleus - centre of the atom, tiny compared to the atom
5
Q
Isotopes
A
- Have extra neutrons
- Same number of electrons and protons
- An example is Carbon-12 and Carbon-13
6
Q
Relative atomic mass
A
- The average mass of one atom of the element, compared to 1/12 of the mass of carbon-12
- If there is more than one isotope for an element, the relative atomic mass will be an average on their abundance
7
Q
Isotopic Abundance
A
- Different isotopes of elements occur in different quantities or isotopic abundances
- To find the relative atomic mass, you need to find average mass
- This is cone by multiplying each relative isotopic mass by its isotopic abundance and add up the results
- Divide by the sum of all the abundances
8
Q
The Periodic table
A
- First proposed by Dimitri Mendeleev
- Began by sorting the elements into groups based on their properties
- He realised he could then order them by atomic mass nd put similar chemical properties in columns
- Some gaps had to be left for elements that had to be discovered
9
Q
Ions
A
- Ions are simply charged particles
- When atoms gain or lose electrons, they form ions
- Ions have full outer shells
- Negative ions (anions) form from electron gain
- Positive ions (cations) form from electron loss
10
Q
Ionic bonding
A
The bonding between a metal and non-metal
11
Q
Ionic Compounds
A
- Have giant ionic lattice structures
- The ions form a closely packed lattice
12
Q
Properties of Ionic Compounds
A
- Ionic compounds have high melting points due to the strong attraction between the ions. It takes a large amount of energy to overcome this
- Solid ionic compounds do not conduct as the ions are in a fixed position, so there are no delocalised electrons to carry current
- They do conduct when molten as there are delocalised electrons to carry current
- Many also dissolve easily in water
13
Q
Benefits and Limitations of models
A
- 2D representations are good at showing what atoms something contains and how they are connected but not the shape or size
- Dot and cross show how componds formed and where the electrons are located but not size or arrangement
- 3D models such as ball and stick show arrangement but only the outer layer of the atom
14
Q
Covalent Bodnding
A
- A covalent bond is formed when a pair of electrons is shared between two atoms.
- Simple molecular substances are made up of molecules containing a few atoms joined by covalent atoms
- These are small
15
Q
Properties of simple molecular substances
A
- Substances with covalent bonds usually have simple molecular structures
- The atoms within are held together by strong covalent bonds however, the molecuels are held together by weak bonds
- It is easy to melt or boil them as the bonds that need to be broken are weak
- As molecules get bigger, intermolecular forces get stonger meaning more energy is required to break them
- Do not conduct electricity
