Module 1 Flashcards
What is a isotope
Istopes are atom with the same number of proton but different number of neutrons
Why do isotopes have similar chemical properties but do not have similar physical properties
Isotopes have similar chemical properties because they have the same electronic structure but they have varying physical properties because they have different masses
What is the the definition of relative isotopic mass
Relative isotopic mass is the mass of one isotope compared to on twelfth of the mass of one atom of carbon -12
What is the definition of the relative atomic mass
Relative atomic mass is the weighted mean mass of one atom compared to one twelfth of the mass of one atom of carbon -12
What is the definition of relative molecular mass
Relative molecular mass is the average mass of a molecule compared to one twelfth of the mass of one atom of carbon -12
What group element produces 1+ ion and also what element that aren’t this particular group produce 1+ ions
Group 1
Hydrogen
Silver
Gold
What group element produce 3+ charge and what is the transition metal with a 3+ charge
Group 3
Iron (lll)
what group and compund produce a 3-
group 5
phosphate
what group and compounds produce -2 ions
group 6
carbonate
sulfate
what group and compound produce a -1 ion
group 7
nitrate
hydroxide
what is a specator ion
ions that are not changing state or not changing oxidation number
what is a mole
the mole is the amount in grams that has the same number of particles as there are atoms in 12 grams of carbon -12
what is relative atomic mass
relative atomic mass is the average mass of one atom compared to one twellth of mass of one arom of carbon -12
what is molar mass and what are the units
molar mass is sthe mass in grams of 1 mole of a substance and is given the unit g mol -1
what is molar gas volume
this is the volume of 1 mole of a gas at a goven tempature and pressure
what is empircal formula
An empirical formula is the simplest ratio of atoms of each element in the compound.
what is avogadro constant
is the value 6.023 x 10^23 which is the number atom in 12g of carbon -12.one mole of any substance has 6.023x10^23 atom of that substance
how do you calculate empircal formula
Step 1 : Divide each mass (or % mass) by the atomic mass of the element
Step 2 : For each of the answers from step 1 divide by the smallest one of those numbers.
Step 3: sometimes the numbers calculated in step 2 will need to be multiplied up to give whole numbers. These whole numbers will be the empirical formula.
What is the definition of molecular formula
A molecular formula is the actual number of atoms of each element in the compound.
what is the equation to calculate concentraion
mol/volume
what is volume measured in
dm^3
what is a solution
solution is a mixture formed when a solute dissolve in a solvent
what is ionic bonding
Ionic bonding is the electrostatic force of attraction
between oppositely charged ions formed by electron transfer.
what infulence the strength of ionic bonding
Ionic bonding is stronger and the melting points higher when the ions are smaller and/ or have higher charges.
what are the property of ionic compounds
*High melting points - There are strong electrostatic attractive forces between the oppositely
charged ions in the lattice
*Non conductor of electricity when solid- The ions are held together tightly in the lattice and can not
move so no charge is conducted
*Good conductor of electricity when in solution or molten – The ions are free to move when in
solution and molten. Charge can be carried
Typical Physical properties of Ionic Compounds
* They are usually soluble in aqueous solvents.
what is a covalent bond
covalent bond is the strong electrostatic attraction between a
shared pair of electrons and the nuclei of the bonded atoms
what is a dative /co-ordinate bond
A dative covalent bond forms when the
shared pair of electrons in the covalent bond
come from only one of the bonding atoms. A
dative covalent bond is also called co-ordinate
bonding.
what is the structure of a ionic compound
giant ionic lattice
what is the bond angle and number of bonded pair in a linear shape molecule
180 and 2
what is the name of the molecule which has 3 bonded pair no lone pair and also 120 degree bond angle
what are the feature of molecule with a tetrahedral shape
4 bonded pair and bond angle 109.5 degrees
what is the name of shape of the molecule which has 3 bonded pairs 1 lone pair electronsa and has bond angle 107 degrees
Trigonal
pyramidal
what are the feature of a molecule with a bent shape
2 bonded pair 2 lone pair and a bond angle od 107
what is the name of shape of a molecule with 6 bonded pairs and has bond angle of 90 degrees
Octahedral
How to explain shape
- State number of bonding pairs and lone pairs of electrons.
- State that electron pairs repel and try to get as far apart as possible (or to a
position of minimum repulsion.) - If there are no lone pairs state that the electron pairs repel equally
- If there are lone pairs of electrons, then state that lone pairs repel more than
bonding pairs. - State actual shape and bond angle.
what is electronegativity
Electronegativity is the relative tendency of an atom in a covalent bond in a molecule to attract electrons in a covalent bond to itself.
what factor influence electronegativtiy
Electronegativity increases as the number of protons increases and the atomic radiusdecreases because the electrons in the same shell are pulled in more.
It decreases if the distance between the nucleus and the outer electrons increases and the shielding of inner shell electrons increases
What are the order of most electronegative elements
F, O, N and Cl are the
most electronegative
atoms
A compound containing elements of similar electronegativity and hence a small electronegativity difference will be purely covalent
how is a polar covalent bond formed and what happen in polar covalent bond
A polar covalent bond forms when the elements in the bond have different electronegativities. When a bond is a polar covalent bond it has an unequal distribution of electrons in the bond and produces a charge separation, (dipole) δ+ δ- ends.
A symmetric molecule (all bonds identical and no lone
pairs) will not be polar even if individual bonds within the
molecular are polar.The individual dipoles on the bonds ‘cancel out’ due to the symmetrical shape of the molecule.There is no net dipole moment: the molecule is
non-polar
A compound containing elements of very different electronegativity and hence a very large
electronegativity difference will be ionic
A compound containing elements of similar electronegativity and hence a small
electronegativity difference will be purely covalent
Induced dipole–dipole interactions occur between all molecular substances and
noble gases. They do not occur in ionic substances
Induced dipole–dipole interactions are also called London forces. They occur between all simple covalent molecules and the separate
atoms in noble gases.
In any molecule the electrons are moving constantly and randomly. As
this happens the electron density can fluctuate and parts of the
molecule become more or less negative i.e. small temporary or
transient dipoles form.
These temporary dipoles can cause dipoles to form in neighbouring
molecules. These are called induced dipoles. The induced dipole is
always the opposite sign to the original one
The more electrons there are in the molecule the higher the chance that temporary dipoles will form. This
makes the induced dipole–dipole interactions stronger between the molecules and so boiling points will
be greate
*Permanent dipole-dipole forces occurs between polar molecules
*It is stronger than induced dipole–dipole interactions and so the compounds have higher boiling points
*Polar molecules have a permanent dipole. (commonly compounds with C-Cl, C-F, C-Br H-Cl, C=O bonds) *Polar molecules are asymmetrical and have a bond where there is a significant difference in
electronegativity between the atoms.
It occurs in compounds that have a hydrogen atom attached to one of the three most
electronegative atoms of nitrogen, oxygen and fluorine, which must have an available lone pair of
electrons. e.g. a –O-H -N-H F- H bond. There is a large electronegativity difference between the
H and the O,N,F
Water can form two hydrogen
bonds per molecule, because
oxygen is very electronegative,
and it has two lone pairs of
electrons.
The molecules are held
further apart than in liquid
water and this explains the
lower density of ice.
s holds up to 2 electrons
p holds up to 6 electrons
d holds up to 10 electrons
f holds up to 14 electrons
An acid releases H+
ions in aqueous solution
The most common strong acids are :
Hydrochloric ( HCl), sulfuric (H2SO4
) and nitric (HNO3
) acid;
Ethanoic acid CH3COOH is a weak acid
An atom fills up the sub shells in order of increasing energy (note 3d is
higher in energy than 4s and so gets filled after the 4s
One we use later
in the course is the Bronsted- Lowry
acid which is a defined as a proton (H+
)
donor
An Alkali is a soluble base that releases OHions in aqueous
solution;
The most common alkalis are sodium hydroxide (NaOH),
potassium hydroxide (KOH) and aqueous ammonia (NH3
)
The Bronsted- Lowry base is defined
as a proton (H+
) acceptor
Strong acids completely dissociate when dissolved in water
Weak acids only slightly dissociate when dissolved in water, giving an equilibrium mixture
A Salt is formed when the H+
ion of an acid is replaced by
a metal ion or an ammonium ion
