Key Concepts In Chemistry Flashcards
What is a MASH equation?
Metal + acid —> salt + hydrogen
What is a BASHO equation?
Base + acid —> salt + water
What is a CASHOCO equation?
Carbonate + acid —> salt + water + carbon dioxide
What are the symbols for these common acids? Hydrochloric acid? Chloride? Sulphuric acid? Sulphate? Nitric acid? Nitrate? Hydroxide? Carbonate?
HCl- Cl- H2SO4 (SO4)2- HNO3 NO3- OH- (CO3)2-
What are the symbols for these common molecules? Water? Ammonia? Carbon dioxide? Chlorine? Hydrogen? Oxygen?
H20 NH3 CO2 Cl2 H2 O2
What is shown in ionic equations and what is taken out?
Only the reactive parts are shown
Any aqueous ions that are present on both sides are taken out
How do you do ionic equations? (2)
Separate any aqueous ions that are present in a balanced equation
Cancel out the aqueous ions which are present on both sides
Why do we use the Bohr model today?
Because it contains shells
Each shell around an element has a f_____ e_____
fixed energy
protons are h_____ and p________ c________
Heavily and positively charged
Neutrons are h_____ and n_______
heavy and neutral
Electrons have ______ ___ mass and a _________ charge
Hardly any mass and a negative charge
Which one is the mass number?
the top one/the MASSive one
Which one is the atomic number?
The bottom one
How do you work out the number of neutrons?
Mass number - atomic number
What is an element?
A chemical substance which cannot be broken down into any simpler substances by chemical reactions
Are elements pure or impure?
Pure
How many melting points do elements have?
1
What is a compound?
Chemicals made from atoms of different elements joined by chemical bonds
Are compounds pure or impure?
Pure
How many melting points do compounds have?
1
What is a mixture?
Made from different substances which are not chemically joined
How many melting points do mixtures have?
A range
Are mixtures pure or impure?
Impure
What is the symbol for ammonium?
NH4+
What is an isotope?
Atoms of the same element with the same number of protons but different numbers of neutrons
What happens to an isotope’s atomic and mass numbers?
Same atomic number but different mass numbers
Calculate the relative atomic mass for:
30% thallium 203
70% thallium 205
(30x203)+(70x204)/100 = 204.4
What does the group number on the periodic table represent?
Number of electrons on the outer shell
What does a period on the periodic table represent?
Number of shells
What did Mendeleev do? (3)
Arranged 50 known elements into a table
Put elements into groups based on properties
Put them in order of atomic mass
What are ions?
Atoms which have lost or gained electrons
Why do atoms gain or lose electrons?
To get a full outer shell
What are anions?
Negative ions
When are anions formed?
When atoms gain electrons, so they have more electrons that protons
What is a cation?
A positive ion
When do cations form?
When atoms lose electrons, they have more protons than electrons
What is ionic bonding?
When a metal and non-metal react together
In ionic bonding, what happens to the metal ions?
They lost electrons to become cations
In ionic bonding, what happens the to non-metal ions?
They gain electrons and become anions
What are ionic compounds?
Giant ionic Lattice structures
What do ionic compounds form?
Crystalline solids
Why do ionic compounds have high melting and boiling points?
Because strong ionic bonds are broken to melt or boil the substance
When do ionic compounds conduct?
They only conduct when molten or dissolved
Why can’t ionic compounds conduct as solids?
The ions can’t move
Are ionic compounds soluble or insoluble?
Some are soluble, some are insoluble
What do ions which are free to move carry?
An electric current
What is covalent bonding?
When a non metal shares electrons with another non metal
When do Giant covalent bonds form?
Between atoms in a giant lattice
Why do giant covalent bonds have high melting and boiling points?
Because lots of strong covalent bonds are broken to melt/boil the substance
Do giant covalent bonds conduct?
They never conduct EXCEPT graphite
Are giant covalent bonds soluble or insoluble?
Insoluble
When do simple covalent bonds form?
They form between atoms to form molecules
What can simple covalent bonds form?
Solids, liquids or gases
Why do simple covalent bonds have low melting and boiling points?
Because of weak intermolecular forces being broken
Do simple covalent bonds conduct?
Never
Are simple covalent bonds soluble or insoluble?
Some are soluble, some are insoluble
What are polymers?
Molecules made up of long chains of covalently bonded carbon atoms
When are polymers formed?
When lots of small molecules called monomers join together
What does metallic bonding have which makes them conduct?
Delocalised electrons
What is between the positive metal ions and the shared negative electrons in metallic bonding?
Strong forces of electrostatic attraction
What state are metallic bonds at room temperature?
All solid except mercury
Why do metallic bonds have high melting and boiling points?
They have a strong attraction which needs to be broken
When do metallic bonds conduct?
When solid or liquid
Are metallic bonds soluble or insoluble?
Insoluble
What is the relationship between polymer chain length and melting point?
The longer the chain, the higher the melting point
What are fullerenes?
Molecules of carbon shaped like closed tubes or hollow balls
Why do fullerenes have a huge surface area?
Could help make great industrial catalysts
