chem Flashcards
what do metals in groups 1,2,3 form
+1, +2, +3
what do non-metals in groups 5, 6, 7 form
-3, -2, -1
what are the first four orbitals called
S, P, D, F
what are s orbitals shaped like
they are shaped like a sphere
what are p orbitals shaped like
they are shaped like a dumb-bell
how many electrons can s orbitals hold
2 electrons
how many electrons can p orbitals hold
up to 6 electrons
how many electrons can d orbitals hold
up to 10 electrons
how many electrons can f orbitals hold
up to 14 electrons
where is the S block found
the first two groups of the periodic table
where is the D block found
transition metals (between S and P) in the periodic table
where is the P block found
on the right hand side of the periodic table (3-8)
where is the F block found
bottom 2 rows of the periodic table
what is a lattice
a regular 3 diensional pattern of ions
what are positive ions
- generically formed by metal atoms losing elecrons and are found in groups 1,2 and 3
- known as cations.
- have a postive charge
what are negative ions
- formed by non metal atoms gaining electrons.
- have a negative charge
- sometimes exists as polyatomic ions (OH-, CO3 2-) (SO4 2-)
- known as anions
what are covalent bonds
covalent bonds are formed when atoms share a pair of electrons
what are metallic bonds
a strong electrostatic attraction between the positive metal and delocalised electron
what are properties of metals
- high melting and boiling point due to strong electrostatic attractions between positive and negative ions and electrons.
- conducts electricity and heat due to delocalised electrons making them free to move.
- malleability as layers of positive ions slides over each other and the delocalised electrons.
what are intermolecular forces
interactions between molecules caused by either permanent/ induced dipoles.
what are polar molecules
- they have permanent dipoles because of the dipole interaction.
- the molecules are attracted to eachother, these weak attracted forces are called permanent dipole-dipole interaction (chemical attraction)
what is a london force
- when electrons move around an atom, they cause an uneven distribution in the atom resulting in temporary dipole.
- this will result in a weak attraction.
- the more electrons, the more likely the process will occur so the stronger the London force.
Why can only O, F and N atoms form hydrogen bonds
theyre small and highly electronegative (they pull pairs of electrons towards them)
what bonds do water bonds form between each other
- they form hydrogen bonds between each other.
- hydrogen bonds have strong intermolecular forces
what do you have to remember when drawing hydrogen bonds between molecules
- show the dipole charge on relevant atoms.
- show the pairs of electrons on O, N or F.
- indicate the hydrogen bond clearly eg using a dashed line.
what is the relative formula mass
the sum of the relative atomic masses of all the atoms in the formula of the substance
what is the formula for mole
mole= mass/ molar mass (relative formula mass)
what is the reactivity series (from least reactive to most reactive)
- lithium
- sodium
- potassium
- rubidium
- caesium
- francium
why does the reactivity increase in the reactivity series
- the atoms get larger as you go down the group
- the outer shell electron gets further away from the nucleus
- the further the electron is from the positive nucleus, the easier it is to lose in a reaction
what does a metal oxide + acid equal
salt + water
what does a metal + acid equal
salt + hydrogen
what are the rules for assigning oxidation numbers (the charge that the atom has)
- an element on its own has an oxidation number of zero
- for a simple ion, the oxidation number is the charge of the ion
- in a compound, the sum of the oxidation states is zero
- the sum of the oxidation numbers equals the charge on a complex ion
what is the Avogadro’s law
equal volumes of different gases at the same pressure and temperature will contain equal numbers of particles
how do you calculate the mass of a product when given the mass of a reactant
- calculate the number of moles of reactant (Mol= Mass/Mr)
- determine mole ratio of reactant to product: ensure the equation is balanced
- calculate the number of moles of the product:
use the mole ratio - calculate the mass of the product:
(Mass=Moles x Mr)
what is the formula for concentration
concentration= moles/ volume
how do you go from kg to g
x 1000
how do you calculate the percentage yield
actual yield/ theoretical yield X100
