Transcript sch4c u1w1d1 introduction to matter and qualitative analysis

Introduction to Matter and
Qualitative Analysis
Welcome
While we are waiting for everyone to arrive,
attempt the following problems before we
begin
 Page 2 Questions 1 through 15

Particle Theory - Review
1.
2.
3.
4.
All Matter is made up of extremely tiny
particles
Each Pure substance has its own kind of
particles, different from the particles of other
pure substances
Particles are always moving -Particles at a
higher temperature are generally moving
faster, on average than particles at a lower
temperature.
Particles attract each other
What is matter?

Anything that has:
Mass
 Volume


So pretty much everything.
Physical Properties
Physical Properties- The characteristics of
a substance.
 There are three states of matter, what are
they?

Solid
 Liquid
 Gas


All three of these states are physical states
of matter.
Physical Properties of
Solids, Liquids and Gases
Phase
Solid
Structure
- Particles
closely packed
- Particles in
fixed positions
Movement of
Particles
Shape of
Sample
Density
- Vibration
-Definite
shape
-Volume of
its own
Liquid -Particles
Closely packed
- Particles not
fixed in position
- Vibration
- Rotation
- Translation
(slower)
- Takes shape - Usually
of container less dense
- Volume of than solid
its own
- Cannot be
compressed
significantly
Gas
- Vibration
- Rotation,
- Translation
(fast)
- Occupies
entire
volume of
container
- Can be
easily
compressed
- Particles
widely spaced
- Particles not
fixed in position
-Usually
more dense
than liquid
or gas
Compressibil
ity
- Much less
dense than
solid or
liquid
-Cannot be
compressed
significantly
Physical Properties
Physical property observations can be made
using several senses.
 Sight
 Smell
 Touch
 Taste
 Sound – This can only give additional
information about the others

Physical Properties
Colour/
appearance
Colourless,
white,
black,
shiny, dull,
Texture
Fine,
course,
smooth,
gritty
Odour
Odourless,
spicy,
sharp,
burnt,
Clarity
Taste
Transparent Sweet,
,
sour, salty,
Translucent buttery
opaque
Typical physical properties

Hardness- The measure of the resistance of
a solid to being scratched or dented. A
harder Material will dent a softer one.

Rank the following from hardest to softest. Steel
nails, chalk, glass, diamond.
 Diamond

˃ Steel nails ˃ Glass ˃ Chalk
Malleability- The ability to be hammered or
bent into different shapes
Example Aluminum foil.
 Brittle – Shatters easily

Typical physical properties

Ductility- Can be pulled into a wire.


Example: Copper wires
Melting and Boiling Points - The
temperatures at which substances change
states.

Ex Water: MP = 0ºC , BP = 100 ºC
Typical physical properties

Crystal Form – The solid forms of minerals


Example – Sodium chloride = table salt
Solubility- The ability a substance to
dissolve in a solvent.

Eample: salt is soluble in water where pepper is
not.
Typical physical properties

Viscosity- Refers to how easily a liquid
flows: the thicker the liquid the more viscous
it is.

Density – The amount of mass per unit
volume of that matter. (kg / cm3)
Chemical properties (3)

A chemical property describes the behaviour
of a substance as it becomes a new
substance
Chemical Properties
1. Combustibility is the ability of a substance
to burn. In order to burn a substance
requires Oxygen
Chemical Properties

Light sensitivity is a chemical property of
that can cause new substances to form
when light hits it.
Chemical Properties
3. Reacting with an acid is a chemical
property where when acid is poured on a
substance it produces a gas and bubbles.
Classification Of Matter
Matter
Pure
Substances
Element
Compound
Mixture
Mechanical
Mixture
Suspension
Solution
Pure Substance

A substance with constant composition.
Can be classified an either an element or as
a compound.

Examples: Table salt (sodium chloride, NaCl),
sugar (sucrose, C12H22O11), water (H2O), iron
(Fe), copper (Cu), and oxygen (O2).
Element

A substance that cannot be separated into
two or more substances by ordinary
chemical (or physical) means. We use the
term ordinary chemical means to exclude
nuclear reactions. Elements are composed of
only one kind of atom.

Examples: Iron (Fe), copper (Cu), and oxygen (O2).
Compound


A substance that contains two or more
elements, in definite proportion by weight. The
composition of a pure compound will be invariant,
regardless of the method of preparation.
Compounds are composed of more than one kind
of atom.
The term molecule is often used for the smallest
unit of a compound that still retains all of the
properties of the compound.

Examples: Table salt (sodium chloride, NaCl), sugar
(sucrose, C12H22O11), and water (H2O).
Mixture

Two or more substances, combined in
varying proportions - each retaining its
own specific properties. The components of
a mixture can be separated by physical
means, i.e. without the making and breaking
of chemical bonds.

Examples: Air, table salt thoroughly dissolved in
water, milk, wood, and concrete.
Homogeneous Mixture

Mixture in which the properties and
composition are uniform throughout the
sample. Such mixtures are termed
solutions.
Examples: Air and table salt thoroughly
dissolved in water
Heterogeneous Mixture
Mixture in which the properties and
composition are not uniform throughout
the sample.
Examples: Sand, Salads, chocolate chip
cookies
 - You will be able to see different substances
in the mixture.

Suspension



A cloudy mixture in which tiny particles of one
substance are held within another.
Can be separated out when the mixture is poured
through filter paper.
A suspension is also a heterogeneous mixture.
Physical changes


In a physical change, the substance involved
remains the same. The substance may change
form or state, however. All changes of state are
physical changes.
There are other physical changes that are not
changes of state. Dissolving is a physical change.
When sugar is dissolved it spreads out in the water
but the sugar is still sugar. If the water was boiled
off there would be sugar left over. Most Physical
changes can be reversed.
Chemical changes

In a chemical Change the substance is changed into one or
more different substances. The new substances have
different properties from the original substance. Most
chemical changes are difficult to reverse and most cannot
be. The new substances are not likely to combine and form
the original substance.

Often during a chemical change you cannot see the change
that has occurred in the substance, but you can observe the
results of the change. There are clues that suggest that a
chemical change has taken place.
Building Scientific Knowledge
Clues that a chemical
change has occurred
Clue
Evidence
Change in colour
Final product(s) may have a
different colour than the colours of
the starting material(s).
Clues that a chemical
change has occurred
Clue
Evidence
Formation of a
solid (precipitate)
Final materials may include a
substance in a state that differs from
the staring material(s): Precipitate
Clues that a chemical
change has occurred
Clue
Evidence
Formation of a
gas
Final materials may include a
substance in a state that differs
from the starting material(s);
commonly, a gas
Clues that a chemical
change has occurred
Clue
Evidence
Release /
Energy (light, electricity,
absorption of sound or most
heat or light commonly heat) is given
off or absorbed.
Clues that a chemical
change has occurred
Clue
Evidence
The change is
difficult to
reverse
The change cannot be reversed
or it is difficult to.
Qualitative Analysis

Qualitative analysis: Involves determining
the composition of an unknown compound or
mixture. This is usually done by investigating
its physical and chemical properties.
Quantitative Analysis
Refers to analyses in which the amount or
concentration may be determined
(estimated) and expressed as a numerical
value in appropriate units.
 Qualitative Analysis may take place without
Quantitative Analysis, but Quantitative
Analysis requires the identification
(qualification) of the analyte for which
numerical estimates are given.

Observation and Inference

Observation:


A statement that is based on what you see,
hear, taste, touch and smell.
Inference:

A judgement or opinion that is based on
observations and/or conclusions
In chemistry we use these two components of
qualitative analysis frequently.

When trying to identify a sample of matter
we
Observe the sample, and then
 Infer what it is based on what we know about
other matter.

Empirical Knowledge and
Theoretical Knowledge

Empirical Knowledge:
Knowledge coming directly from observations
 It describes what is being observed


Theoretical Knowledge:
Knowledge based on ideas that are created to
explain observations
 We explain things by using theories that we
know.


Theory:
A explanation of a large number of related
observations
 Ex. Theory of relativity , Theory of evolution


Model:
A model is a way of representing a theory or idea.
 A model can change over time
 Ex. The model of the atom , a globe of the earth.

How to light a Bunsen
burner
Step 1
 The first step is to check for safety - lab
coat on, long hair tied back, safety glasses
on, books and papers away from the flame,
apparatus set up not too close to the edge of
the table...

How to light a Bunsen
burner
Step 2
 The second step is to look at the
holes. Check that the holes are
closed. The holes can be adjusted to let in
more or less air by turning the collar(see
photos below).
Open
Closed
How to light a Bunsen
burner
Step 3
 Hold the sparker in one hand above the
burner and turn on the gas with the other.
 As soon as you turn the gas on start
sparking.


NOTE: some have an extra gas valve to
them. Look before you light it.
How to light a Bunsen
burner
Step 4
 Adjust the flame by turning the collar so
that you have the appropriate flame for the
experiment (usually the medium blue
flame).

How to light a Bunsen
burner
Step 5
 During the experiment, stay vigilant so that
if a problem occurs, you are ready to turn off
the flame quickly. This means that you
should not leave your bench unattended.

Now its your turn

Everyone in the class must show that the
know how to do this properly before they can
continue with the activity.
Homework
“The Burning Candle” lab on page 11
Do this now
Class / Homework – page 12 # 1- 6
Do this later
Questions
1.
Classify each of the following statements as
either an inference or an observation
A.
B.
C.
D.
E.
The wood does not burn because it is wet
The boiling point of methanol is 67.5 C
The light that a glow stick emits can be
prolonged if the glow stick is placed in a fridge
The temperature of a metal increased due to
an increase in the vibrations of the atoms within
it.
There is 125mL of water in the flask
2. “Theories cannot be prove; they can only be
supported with experiment evidence”
Comment on this statement
3. Explain how models are useful for
conveying a theory or idea
4. Using a concept map, illustrate how the
following terms are interconnected: empirical
knowledge, inference, observation, theory.
5. In a court of law, responses from witnesses
who state opinions are often stuck from the
record. Give reasons why a lawyer may want a
witness to make statements based on
observations rather than inferences.
6. Qualitative chemical analysis involves
identifying a substance through diagnostic
tests. Diagnostic test are based on physical and
chemical properties of substances. Is qualitative
analysis empirical or Theoretical. Give reasons.
The periodic Table
The Foundation of the
periodic Table
Dmitri Mendeleev devised and published the
periodic table in in 1869.
 Mendeleev found he could arrange the 65
elements that were then known in a grid or
table so that each element had:
 1. A higher atomic weight than the one on its
left.
 2. Similar chemical properties to other
elements in the same column.


He did not know about orbits at this time
Dmitri Mendeleev

He noticed gaps in the table and predicted
where elements would fit and their properties
before they were discovered.
Henry Moseley

In 1913, Henry Moseley, who worked with
Rutherford, showed it is atomic number
(charge) and not (as Mendeleev had
proposed) atomic weight that is most
fundamental to the chemical properties of
any element. Like Mendeleev, Moseley was
able to predict correctly the existence of new
elements based on his work.
The Periodic Table

Today the elements are still arranged in
order of increasing atomic number (Z) as
you go from left to right across the table.

We also know an element's chemistry is
determined by the way its electrons are
arranged - its electron configuration.
Other table features
Important Features of the Table
 The elements are also organized in two
fashions horizontal vertical and horizontal lines
called groups and periods.
 Groups- elements with similar chemical
properties in a vertical column in the main part
of the table;
 Period – elements, arranged in a horizontal
row, whose properties change from metallic on
the left to non-metallic on the right
Other table features

Staircase line – A zigzag line that separates
metals (to the left) from non-metals (to the
right) ;
Chemical Groups
The alkali Metals
 Soft, silver colour elements; solids at SATP;
exhibit metallic properties; react violently
with water to form basic solutions and
liberate hydrogen gas; react with halogens to
form compounds similar to sodium chloride;
stored under oil in a vacuum to prevent
reaction with air.
Chemical Groups
The alkaline Earth Metals
 Light, very reactive metals; solids at SATP;
exhibit metallic properties; form oxide
coating when exposed to air; react with
oxygen to form oxides with the general
formula MO(s); all except beryllium will react
with hydrogen to form hydrides with the
general chemical formula XH2; react with
water to liberate Hydrogen gas.
Chemical Groups
Transition Metals
 Exhibit a wide range of chemical and
physical properties; characteristically strong,
hard metals with high MP; good conductors
of electricity; variable reactivity form ions
with variable charges many react with
oxygen to form oxides; some will react with
solutions of strong acids to form hydrogen
gas.
Chemical Groups
Halogens
 May be solids, liquids, or gasses at SATP;
exhibit non-metallic properties – not lustrous
and non-conductors of electricity; extremely
reactive, with fluorine being the most
reactive; react readily with hydrogen and
metals.
Chemical Groups
Noble Gases
 Gases at SATP; low melting and boiling
point; extremely uncreative, making them
especially interesting to chemists;

Chemical Groups
Representative Elements
 Include metals and non-metals from Groups
1, 2, and 13 through 17; may be solids,
liquids, or gases as SATP; called
representative because they most closely
follow the periodic law; many form colourful
compounds.
Chemical Groups
Rare Earth Elements
 The rare earth elements can be divided into
lanthanides (elements 58 - 71) and actinides
(elements 90 - 103). The naturally occurring
rare earths are found on earth in only very small
amounts. The actinides include most of the
well-known elements that take part in or are
produced by nuclear reactions. No element with
atomic number higher than 92 occurs naturally.
These elements are produced artificially in
nuclear reactors or particle accelerators.

Work
Homework: Do the Questions on Page
2 Questions 1 through 15
 Homework: Read Appendix B2: Safety In
the Laboratory
Pages 480 to 484
 Homework: Page 12
Section 1.2 Questions 1 through 6
 Candle lab
