Inorganic Chemistry Flashcards
Name the processes
responsible for the following
phase changes: solid ⇄ gas
Sublimation (s to g)
Deposition (g to s)
What is diffusion?
It is the overall movement of particles from an area of high concentration to an
area of low concentration.
E.g. a gas will diffuse through all the space it can find.
E.g. if you spray some perfume in one corner of the room, soon you will be able to
feel the smell at the other end of the room.
What is a solubility curve?
It is a curve that shows how the solubility of a substance (in grams per 100 g of
water) changes with temperature.
Outline the main assumptions of the kinetic
theory of matter.
a) Matter is made up of atoms, molecules and ions of different sizes.
b) At the same temperature, small particles move faster than large particles
c) As temperature rises, the particles have more kinetic energy and move faster
d) Solids are made up of ordered arrangement of closely packed particles
e) Liquids do not have particles arranged regularly. Particles can move around.
f) In gases, the particles are far apart. They move fast. Their motion is random.
Explain what is meant by centrifuging
It is a method for separating out particles of different densities in a substance.
It can be used to separate suspended solids (very small particles of solid) from the
liquid they are suspended in.
It is used when the particles are so small that they can’t be separated via filtration.
In a centrifuge, the sample is spun at high rates. This forces the solid particles to
settle down at the bottom of the tube. The liquid can be decanted.
What is an atom?
An atom is the smallest particle of a chemical element that can exist.
What is an element?
An element is a substance made up of only one type of atom.
How are the element listed and approximately how
many are there?
They are listed in the periodic table; there are approximately 100.
Elements can be classified into
two groups based on their
properties; what are these
groups?
Metals and non-metals
Elements may combine
through chemical reactions to
form new products; what are
these new substances called?
Compounds
What is a compound?
Two or more elements combined chemically in fixed proportions which can
be represented by formulae
Do compounds have the same properties as their
constituent elements?
No, they have different properties.
What is a mixture? Does it have the
same chemical properties as its
constituent materials?
A mixture consists of two or more elements or compounds not chemically
combined together; the constituent materials keep their own chemical
properties, but the mixture may have different chemical properties (e.g.
melting point) as a whole.
What are the methods through which mixtures
can be separated (there are five)? Do these
involve chemical reactions?
Filtration, evaporation/crystallisation, simple distillation, fractional
distillation and chromatography; they do not involve chemical reactions
Describe and explain simple
distillation.
Simple distillation is used to separate liquid from a solution – the liquid
boils off and condenses in the condenser. The thermometer will read the
boiling point of the pure liquid. Contrary to evaporation, we get to keep the
liquid (it drips and is collected into a separate beaker).
Describe and explain crystallisation/evaporation
Evaporation is a technique for separation of a solid dissolved in a solvent from a
solvent (e.g. salt from H2O).
The solution is heated until all the solvent evaporates; the solids stays in the vessel.
Crystallisation is similar, but we only remove some of the solvent by evaporation to
form a saturated solution (the one where no more solid can be dissolved). Then,
we cool down the solution. As we do it, the solid starts to crystallise, as it becomes
less soluble at lower temperatures. The crystals can be collected and separated
from the solvent via filtration.
Describe and explain
fractional distillation
Fractional distillation is a technique for separation of a mixture of liquids.
It works when liquids have different boiling points.
The apparatus is similar to the one of simple distillation apparatus, with the additional
fractionating column placed on top of the heated flask.
The fractionating column contains glass beads. It helps to separate the compounds.
In industry, mixtures are repeatedly condensed and vapourised. The column is hot at the
bottom and cold at the top. The liquids will condense at different heights of the column.
Describe and explain filtration
Filtration is used to separate an insoluble solid suspended in a liquid. The
insoluble solid (called a residue) gets caught in the filter paper, because
the particles are too big to fit through the holes in the paper.
The filtrate is the substance (liquid) that comes through the filter paper.
Apparatus: filter paper + funnel.
Describe and explain chromatography
Chromatography is used to separate a mixture of substances dissolved in a solvent.
In paper chromatography, we place a piece of paper with a spot containing a mixture
in a beaker with some solvent. The bottom of the paper has to be in contact with
the solvent. The solvent level will slowly start to rise, thus separating the spot
(mixture) into few spots (components).
Describe a paper chromatography experiment
a) A start line is drawn near the bottom of the paper. The mixture is spotted on the line.
b) A beaker is filled with small amount of solvent (it cannot touch or go above the start line
when paper is placed in a beaker)
c) Paper is hung on a rod and placed in a beaker.
d) Solvent travels up the paper, thus separating the components.
e) Before solvent level reaches the end, the paper is taken out and the finish line is
marked. The paper is dried.
f) The procedure works when the components dissolve differently in the solvent. More
soluble components travel further up the paper. Less soluble components have a
stronger attraction for the paper and travel less slowly with the solvent, therefore less
further up the paper.
g) Paper is called the stationary phase - it doesn’t move. Solvent is the mobile phase.
How is Rfcalculated?
Distance moved by the spot (solute component) / distance moved by solvent.
In a paper chromatography experiment, a
compound A was found to have an Rf
value of
0.85 - what does it tell you about the compound?
It has a higher affinity for the solvent than for the paper.
What is a separating funnel?
A separatory funnel is an apparatus for separating immiscible liquids.
Two immiscible liquids of different densities will form two distinct layers in
the separatory funnel.
We can run off the bottom layer (the liquid with greater density) to a
separate vessel.
Describe the plum-pudding model
The atom is a ball of positive charge with negative electrons embedded in
it.
Describe the Bohr/nuclear model and how it
came about
The nuclear model suggests that electrons orbit the nucleus in energy
levels (at specific distances from nucleus) – it came about from the alpha
scattering experiments conducted by Ernest Rutherford and two students.
Later experiments led to the discovery of
smaller, positive particles in the nucleus; what
are these particles called?
Protons
What did the work of James Chadwick provide
evidence for?
The existence of neutrons in the nucleus.
Describe the structure of an atom
Describe the structure of an atom
State the relative masses and relative charges
of the proton, neutron and electron
Masses: 1, 1, very small (respectively)
Charges: 1, 0 , -1 (respectively)
Explain why atoms are
electrically neutral.
They have the same number of electrons and protons
What is the radius of an atom?
0.1 nm
What is the radius of a nucleus and what is it
compared to that of the atom?
1 x 10-14 m and less than 1/10000 of the radius of the atom.
What name is given to the number of protons in
the nucleus?
Atomic number
Atoms of the same element have
the same number of which particle
in the nucleus?
Protons
Where is the majority of mass of an atom?
The nucleus
What is the mass number?
The total number of protons and neutrons in the nucleus.
How does one calculate the number of neutrons
using mass number and atomic number?
Subtract the atomic number from the mass number.
What is an isotope? Do isotopes of a certain
element have the same chemical properties?
Atoms of the same element (same proton number) that have a different
number of neutrons.
They have the same chemical properties as they have the same
electronic structure.
What is the relative atomic mass?
The average mass value of one atom (taking into account the abundance of
isotopes), compared to 1/12 of the mass of one carbon-12 atom.
Give the electronic configurations of
He (2), Be (4), F (9), Na (11), and Ca
(20) to demonstrate how shells are
occupied by electrons.
2 2,2 2,7 2,8,1 2,8,8,2
Describe the properties of noble gases. Discuss
the trends in properties down the group.
Non-metals, colourless gases at room temperature, low boiling points,
unreactive (full outer shell; they don’t easily accept or lose electrons).
The boiling point increases down the group, as the atoms get heavier.
Explain the following: solute, solvent, solution,
miscible, immiscible, soluble, insoluble.
A solute is a substance that is dissolved in a solvent. Together they form a
solution.
Miscible refers to the substances (particularly liquids) that mix together in all
proportions, e.g. water and alcohol. Water and oil are immiscible, i.e. they do not
mix.
Soluble refers to the substance that can be dissolved in a solvent, e.g. salt in
water. An insoluble substance won’t dissolve in a particular solvent.
The columns of the periodic table are called?
Groups
The rows of the periodic table are called…?
Periods
Are elements in the same
group similar or different?
They may have similar chemical properties, as they have the same
number of outer shell electrons.
In terms of energy levels, what are the
differences between elements of the same
period?
They have the same number of energy levels
Electrons occupy particular energy levels, with each
electron in an atom at a particular energy level; which
available energy level do electrons occupy?
The lowest available energy level
The elements of Group 0 are more commonly
known as…?
The noble gases
What makes the periodic table periodic?
Similar properties of elements occur at regular intervals
Elements in the same group have the same
number of electrons in their outer shell; what
does this tell us about their chemical properties?
They have similar chemical properties
In terms of shells, what is the difference
between elements in the same period?
They have the same number of shells
What change in shell number is seen as one
moves down a group?
The number of shells increases
Early periodic tables were incomplete and
elements were placed in inappropriate groups if
what was to be followed?
The strict order of atomic weights
Knowledge of what made it possible to explain
why the order based on atomic weights was not
always correct?
Isotopes
Mendeleev overcame some problems with the
table by doing what? He also changed the order
of some elements based on what?
Leaving gaps; atomic weights
The majority of elements are…?
Metals
Elements that react to form positive ions are…?
Metals
Elements that do not form positive ions are…?
Non-metals
Elements in Group 1 are known as…?
The alkali metals
Elements in Group 7 are known as…?
The halogens
What is ionic bonding?
Ionic bonding is the transfer of electron(s) from a metal atom to a
non-metal atom to form positive and negative ions.
There is a relatively strong electrostatic attraction between the positive
and negative ions which is called an ionic bond.
How are ionic compounds held together?
They are held together in a giant lattice.
It’s a regular structure that extends in all directions in a substance.
Electrostatic attraction between positive and negative ions holds the
structure together.
