Topic 1 - Key Concepts Flashcards
Ammonia formula
NH3
Ammonium ions formula
NH4+
Nitrate formula
NO3-
Sulfate formula
SO4 2-
Hydroxide formula
OH-
Carbonate formula
CO3 2-
Ionic equation
If a substance is ionic and aq, then it can be split into its individual ions to get he equation.
Atom models
Dalton model - solid spheres, JJ Thompson - Electrons inside sphere(plum pudding model), Rutherford - Positive nucleus, electrons float, Bohr - electron shells
Nucleus size and mass
Tiny compared to rest of atom but most of the mass in the atom is inside it
Mass number
Total number of protons and neutrons in an atom
Atomic number
Proton amount. Amount of protons is unique to each atom.
Isotope
An atom with the same number of protons but a differetn number of neutrons in the nucleus. There are different isotopes for some different elements, which leads to their mass numbers not being whole.
Relative atomic mass calculation based on isotopic abundances
Multiply each isotope mass by its quantity. Then add all of them upp and divide by the sum of the quantities.
How did mendeleev arrange his table
Based on atomic mass which put elements with similar properties in columns. Some were wrong due to isotopes, and gaps were left for undiscovered elements, which he predicted the properties of.
Periodic table arrangement now
Ascending atomic number, rows called periods which represent shells on the atom, columns called groups which have elements with similar properties
Ionic bonding
When a metal and non-metal bond by the metal losing electrons and giving them to the non-metal. The oppositely charged ions are strongly attracted to eachother by electrostatic forces.
Ionic compounds properties
Lattice structure, high melting and boiling points, delocalised electrons so can carry electric charge
Covalent bonding
When a pair of electrons is shared between two atoms. Leads to formation of molecules( around 10 power -10 m size)
Giant covalent structures
Large molecules held by strong covalent bonds. High boiling and melting points. Dont conduct electricity. Eg diamonds, graphite, graphene(all forms of carbon)
Metallic bonding
Giant structures held very strongly together by electrostatic attraction between positive metal ions and electrons.
Graphite
Three covalent bonds creating sheets of carbon atoms
arranged in hexagons. The sheets slide over eachother meaning it is soft and slippery. Used for lubricants
Diamond
Network of carbon atoms that from 4 covalent bonds. Rigid lattci structure leads to it being really hard. Used to strengthen cutting tools
Fullerenes
Molecules of carbon in closed tubes or hollow balls.
Buckminsterfullerene
C60. Forms a hollow sphere made of 20 hexagons and 12 pentagons. Stable molecule that forms soft crystals.
Metal properties
Mostly very high melting and boiling points. In pure metals, layers of atoms can slide over eachother, making metals malleable. Good conductors.
relative formula mass Mr =
All the atoms relative atomic masses in the formula
What is empirical formula
The simplest ratio of atoms
Law of consrvation of mass
No atoms are created or destroyed . In a closed system, the mass will stay the same
What leads to the mass increasing during a reaction
The reactant is a gas in the air, so it is used by the reaction and more atoms are present in the product.
What leads to mass decreasing during a reaction
When the product is a gas, it is released to the air and therefore the product has less atoms than the original reactants.
Concentration unit
g dm-3
Concentration =
Mass of solute / Volume of solution
Avogadros constant shows
The amount of atoms in a mole
Avogadros constant =
6.02 x 10^23
Moles =
Mass(g) / Mr
Particles of a substance =
Moles x 6.02 x 10^23
How is the magnesium oxide experiment carried out to find empirical formula
Weight magnesium.
Heat it in a crucible whilst letting oxygen in until it turns white
Weigh the magnesium oxide
Use the masses and Mr of magnesium and oxygen to find the empirical formula
Reactions stop when
The limiting reactant is used up
The amount of product formed is directionally proportional to
The amount of limiting reactant
How to find the balanced symbol equation of a reaction using the masses of the substances
Find moles of each substance using mass/Mr. Divide each number of moles by the smallest number of moles in a single substance. Make all the numbers whole and write them before each substance.
