Chapter 1Chemistry: What is Chemistry

(A whole lot of fun!)

Objectives

• Describe chemistry

• Classify and describe the types of matter

• Describe physical and chemical properties

• Describe physical and chemical changes

• Recognize clues a chemical change has occurred

What is Chemistry?

• The study of the matter, its composition, properties, and the changes it undergoes.

• Applied Chemistry is the using chemistry to attain certain goals, in fields like medicine, agriculture, and manufacturing

• Pure chemistry gathers knowledge for knowledge sake

Types of Chemistry

• Analytical Chemistry studies composition of substances.

• Inorganic Chemistry substances without carbon

• Organic Chemistry compounds containing carbon

• Biochemistry- Chemistry of living things• Physical Chemistry studies behavior of

substances

Chemistry is

• A natural science with a language and its own vocabulary.

• A way of thinking.

What is Matter?

• Matter is anything that takes up space and has mass.

• Mass is the amount of matter in an object.

– Mass is resistance to change in motion along a smooth and level surface.

– Volume – measure of 3D space

Types of Matter

• Pure Substance- a particular kind of matter - pure

• Mixture- more than one kind of matter

Substances• Elements- simplest kind of matter• Cannot be broken down • All one kind of atom.• Compounds are substances that can be

broken down by chemical methods• When they are broken down, the pieces

have completely different properties than the compound.

• Made of molecules- two or more atoms

Atoms

• The smallest unit of an element that maintains the properties of that element.

Elements

• A pure substance made of only one kind of atom

• Currently 118 elements

• 90 natural 28 synthetic

• Found on periodic table

• Identified by 1,2, or 3 letter chemical symbol

Chemical symbols

• There are 118 elements

• First letter always capitalized second and third never

• Don’t need to memorize

• Some are from Latin or other languages

H= Hydrogen Au= Gold Uub=Ununbibium

Elements cont.

• Majority are metals (found on the left side of periodic table)

• Nonmetals on the right of stair step line

Compounds

• A substance that is made from the atoms of two or more elements that are chemically bonded

• Chemical Formula – Indicates type and number atoms in a compound

• Ex. H2O = 2 Hydrogen atoms and 1 Oxygen atom

Compounds cont.

• Molecular Compounds made from nonmetallic atoms

• Ionic Compounds contain ions

– (usually a metal and nonmetal)

Molecular or Ionic?

C6H12O6

Molecular

MgCl2Ionic

CO2

Molecular

Metals

• Luster

• Good conductor of heat and electricity

• Malleability

• Ductility

• High tensile strength

Nonmetals

• Many nonmetals are gases at room temperature

• Solid nonmetals tend to be brittle

• Poor conductors of heat and electricity

Mixtures

• A blend of two or more kinds of matter, each of which retains its own identity and properties

• The components of mixtures can usually be separated through physical means

– filtration, distillation, chromatography

Filtration

• Uses a filter to separate substances– Solid from a liquid

Distillation

• Separates based on boiling points

– liquids

Chromatography• Separates based on polarity

– What?!?!?!?!?!•We’ll get to that later-Liquids or gases

Heterogeneous Mixtures

• Called suspensions and colloids

• Not uniform throughout

– Ex. Chocolate chip cookie, gravel, soil

Homogeneous Mixture

• Called solutions

• Mixtures that are uniform throughout

– Kool-aid, air, gold ring

Solutions

• Like all mixtures, they keep the properties of the components.

• Can be separated by physical means

• Not easily separated- can be separated.

Solutions

• Homogeneous mixture– Mixed molecule by molecule– Can occur between any state of matter.

• Solid in liquid- Kool-aid• Liquid in liquid- antifreeze• Gas in gas- air• Solid in solid - brass• Liquid in gas- water vapor

Flowchart of Matter

Which is it?

ElementCompoundMixture

Physical Properties

• A property that can be observed and measured without changing the substance.

– Ex. melting point, boiling point, density, hardness, color, odor

• Freezing Point vs. Melting Point?

States of matter

• Solid- matter that can not flow and has definite volume.

• Liquid- definite volume but takes the shape of its container (flows).

• Gas- a substance without definite volume or shape and can flow.

Physical Change

• A change that changes appearances, without changing the composition.

1. Freezing – liquid to solid

2. Melting – solid to liquid

3. Boiling – liquid to vapor

4. Condensation – vapor to liquid

5. Sublimation – solid to vapor

6. Deposition – vapor to solid

Chemical Properties

• Relates to a substances ability to undergo changes that transform it into different substances

– Ex. combust, oxidize, neutralize

Chemical Change

• A change in which one or more substances are converted into different substances

Ex. combustion, oxidation, neutralization

Chemical Reactions

• Carbon + Oxygen Carbon Dioxide

– Read as “Carbon and (plus) oxygen yields carbon dioxide

– Carbon and Oxygen are reactants

– Carbon Dioxide is the product

Chemical Reactions

• When one or more substances are changed into new substances.

– Reactants- stuff you start with

– Products- What you make

• NEW PROPERTIES

• Not easily reversed

Indications of a chemical reaction

• Energy absorbed or released

• Color change

• Gas is released

• Light given off

• Precipitate- solid that separates from solution p.255 in text

Example

Homework

• Page 21 #’s 25,31,34,53,54,56,68