Chapter 1

Chemistry is a Physical Science

Objectives

• Define chemistry• List the branches of chemistry• Compare and contrast basic research,

applied research, and technology• Distinguish between chemical and

physical properties of matter• Distinguish between a pure substance and

a mixture

Chemistry

• Study of the composition, structure and properties of matter – Atoms and their composition, structure and

properties• Study of the changes matter undergoes

– Changes in bonding, charge of atoms and groups of atoms

• Chemistry is a science: – A systematic study of part of the universe.

What’s the difference?

• Science: Study of the universe to answer questions and understand how it works.– Basic science: carried out for the sake of

increasing knowledge– Applied science: carried out to solve a

particular problem• Technology: Use science to make life

easier or better.

Branches of Chemistry• Organic—carbon containing compounds ( more

specifically C and H containing)• Inorganic—not organic • Physical—relationships between energy and

matter• Analytical—identification of composition• Biochemistry—substances and processes

occurring in living things• Theoretical—design and predict properties of

new compounds

What is a chemical?• A chemical is any substance with a definite

(unchanging) composition• May also be called a pure substance• Includes elements and compounds, but not

mixtures• Compounds are chemical combinations of two or

more elements– different characteristics than elements that make it

• Mixtures are blends of two or more kinds of matter – but each kind retains its unique identity and properties

More about mixtures

• Mixtures are classified as being:– Homogeneous: uniform in composition– Heterogeneous: dissimilar in composition

Examples:

What’s the matter?

• Matter is anything with volume and mass.– Volume:– Mass:

• The basic building blocks of matter are atoms.• Atoms are the smallest parts of an element that

have the properties of that element.• An element is a pure substance made of only one

kind of atom– (more specifically with one number of protons in the

nucleus)

Compounds

• Compound is a pure substance made from the atoms of two or more elements that are chemically bonded.

Compounds

• How do things go from being atoms to compounds?

• Chemical change occurs– A chemical change is one in which new pure

substances are formed– A chemical change is caused by a chemical

reaction– Example: Burning match

Chemical reaction

• Reactant + Reactant Product + Product

• Reactants are the substances that exist before the reaction

• Products are the substances that exist after the reaction

• During a chemical reaction, the physical properties of the reactants may change as well as the chemical properties.

Chemical Properties

• Measurable characteristics recorded while a substance is undergoing a chemical reaction

• Examples:– Reactivity with oxygen– Reactivity with hydrochloric acid

Physical Properties

• Characteristics that may be observed without changing the composition of the substance.

• Examples are mass, boiling point, melting point, state, color, density

• States of matter:– Solid– Liquid– Gas– Plasma

Energy (E)

• Definition: the capacity to do work– Work is:

• Whenever a physical or chemical change occurs, there is an associated energy change.

• Think about melting ice or burning paper

Measurement• Properties are measured using SI units• SI = Systeme Internationale = metric system• This is the system we will use—more detail later• Length

– Meter (metre)

• Mass– Kilogram

• Volume (fluid)– Liter (litre)

• Time– Second

• Quantity (number of particles)– Mole