PowerPoint to accompany

Chapter 1:Part 1

Matter & Measurements

Introduction: Matter,

Measurement and Molecules

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Hubble Image

Pillars of Creation inM16Eagle Nebula

A Star-forming region

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Chemistry

The study of matter and the changes it undergoes.

Figure 1.2

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

The Scientific Method

A systematic approach to solving problems

Figure 1.9

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Matter

Anything that has mass and takes up space.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

MatterAtoms are the building blocks of matter.Each element is made of the same kind of atom.A compound is made of two or more different kinds of elements.

Figure 1.1

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Pure Substances, Elementsand Compounds

The elemental composition of a pure compound is always the same and this is known as the Law of Constant Composition (or Law of Definite Proportions)

Joseph Proust (1754 - 1826)

Pure SubstanceMatter that has distinct properties and a compositionthat doesn’t vary from sample to sample, e.g. salt. ElementA substance that cannot be decomposed into simplersubstances, e.g. oxygen gas. CompoundA substance that is composed of two or more differentelements, so it contains two or more different kinds of

atoms, e.g. water.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Solid Carbon Polymorphs(different crystal structures, 1 element)

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Monatomic & Molecular ElementsCompounds and Mixtures

He H2 BF3 All 3

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Mixtures A mixture is a combination of two or more

substances in which each substance retains its own chemical identity and can be separated from each other.

There are two types:

- heterogeneous: a mixture which does not have the same composition, properties and appearance throughout: muesli, sand, rocks.

- homogeneous: a mixture which is uniform throughout: solutions, air, smoke, alloys

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Banded MalachiteCu2(CO3 )(OH)2& Crystals

Copper Sulphate Hydrate & Solution Cu(SO4) – 6H2O

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Classification of Matter

Figure 1.5

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Properties and Changes of

Matter

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Properties of Matter

Physical Properties Can be observed without changing a

substance into another substance. Boiling point, density, mass, volume, etc.

Chemical Properties Can only be observed when a substance is

changed into another substance. Flammability, corrosiveness, reactivity with acid,

etc.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Properties of Matter

Intensive Properties Independent of the amount of the substance

that is present. Density, boiling point, colour, etc.

Extensive Properties Dependent upon the amount of the

substance present. Mass, volume, energy, etc.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

GaAs a semi-conductor has nearly overlapping molecular bonds

Being a semi-conductoris an intrinsic propertyof this compound, dueto its bonds & crystal

structure.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Changes of Matter

Physical Changes Changes in matter that do not change the

composition of a substance. Changes of state, temperature, volume, etc.

Chemical Changes Changes that result in new substances.

Combustion, oxidation, decomposition, etc.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Chemical Reactions (Chemical Change)

In the course of a chemical reaction, the reacting substances are converted to new substances.

Figure 1.6

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Compounds

Compounds can be broken down into more elemental particles; for example, during the electrolysis of water, the smaller particles hydrogen gas and oxygen gas are created.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

2H2(g) + O2 (g) H2O (g) + E

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Separation of Mixtures

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Separation of Mixtures

1. Distillation

Separates ahomogeneousmixture on the

basis of differencesin boiling point.

Figure 1.8

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Separation of Mixtures

2. Filtration

Separates solid substances from liquids and solutions.

Figure 1.7

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Units of Measurement

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

SI Units

Système International d’Unités Uses a different base unit for each quantity

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Metric System

Prefixes convert the base units into units that are appropriate for the item being measured.

Table 1.3

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

SI Units - Length and Mass

The SI base unit of length is the metre (m).

Mass (m) is a measure of the amount of material in an object. The SI base unit of mass is the kilogram (kg).

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

SI Units - Temperature

The Kelvin is the SI unit of temperature.

It is based on the properties of gases.

There are no negative Kelvin temperatures.

K = C + 273.15

Figure 1.10

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Derived SI Units Volume

The most commonly used metric units for volume are the litre (L) and the millilitre (mL). A litre is a cube 1 dm long

on each side. A millilitre is a cube 1 cm

long on each side.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Derived SI Units Density

Density is a physical property of a substance and is determined through the following formula:

density =mass

volume

=mVor symbolically

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Uncertainty in Measurement

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Uncertainty in Measurements

Different measuring devices have different uses and different degrees of accuracy.

Figure 1.12

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Significant Figures

All digits of a measured quantity, including the uncertain, are called significant figures.

The greater the number of significant figures, the greater the certainty of the measurement.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Significant Figures All nonzero digits are significant, e.g. 123.45

Zeros between two significant figures are themselves significant, e.g. 103.405

Zeros at the beginning of a number are never significant, e.g. 00123.45 = 123.45

Zeros at the end of a number are significant if a decimal point is written in the number, e.g. 123.450 has six significant figures but 123450 has only five significant figures

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Significant Figures

When addition or subtraction is performed, answers are rounded to the least significant decimal place.

When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation.

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Precision and Accuracy Accuracy refers to the proximity of a measurement

to the true value of a quantity.

Precision refers to the proximity of several measurements to each other.

Figure 1.15

Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia

Reading Errors & Interpolation

27°+/- 1°C