The Science of Chemistry

Chapter 1

Unit Essential Question:

How is chemistry applied to the matter that makes up the world

around us?

Lesson Essential Questions:

What does the science of chemistry study?

How does matter change?

Chemistry is the study of matter- its properties and changes it goes through

Atoms are the most basiccomponent of matter.

Section 1: What is Chemistry?

A chemical is any substance that has definite composition◦ Natural– water (H2O), carbon dioxide (CO2)◦ Synthetic– plastics, teflon (tetrafluoroethylene)

They’re everywhere! Some good, some bad

Section 1: What is Chemistry?

Solid, liquid, gas, plasma Macroscopic – can see with your eye (macro =

large) Microscopic – cannot be seen with the unaided

eye (micro = small)

Figure 2 pg.6 – atoms in each state

States of Matter

solid liquid gas

Solid Liquid Gas

Fixed volume Fixed volume Indefinite volume

Fixed shape Indefinite shape

Indefinite shape

Rigid structure, organized, vibrate in

place

Loosely held together, slide

past each other

Independent, weak

attractions

States of MatterCharacteristics:

Physical Changes◦Identity of matter stays the same. Arrangement, shape, or location might

change◦Examples: Cutting, dissolving, boiling, crushing

Changes of Matter

Identity of matter changes.◦New substances are formed = chemical

reaction◦Reactants – starting materials◦Products – ending materials◦Example:

mercury(II) oxide → mercury + oxygen

Chemical Changes

1. Evolution of a gas (bubbles, odor)2. Formation of a precipitate (solid formed

from 2 solutions/liquids – looks cloudy)3. Release or absorption of energy (change in

temperature or light given off)4. Color change

Evidence of a Chemical Change

Lesson Essential Question:

How can we measure and describe matter?

Matter – anything that has mass and takes up space (has volume)

Volume – a measure of the size of an object◦Uses mL, L, cm3 as units (1mL = 1cm3)◦Measured using ruler or

graduated cylinder

Section 2: Describing Matter

Mass- measure of the quantity of matter in an object◦Uses: kg, g, mg

Weight – measure of the gravitational force exerted on an object◦Can change with location Gravity changes

◦Units: Newtons (N)

Mass & Weight

Earth’s gravity is 9.8m/s2

The moon’s gravity is 1.6m/s2 Jupiter’s gravity is 25m/s2

A person weighs 150lb on Earth The same person weighs 25lb on the moon And he/she weighs 360lb on Jupiter

These are NOT masses!

Example of Different Weights

Unit – quantity adopted as a standard of measurement

Quantity – something that has size, magnitude or amount

SI – Système International (international system)

1960 decided to unify measurement worldwide◦ 7 base units

All others are a combination of these Use prefixes to change magnitude

Measurement

Not the same as the metric system!

Quantity Symbol Unit Abbreviation

Length l Meter m

Mass m Kilogram kg

Time t Second s

Temperature T Kelvin K

Amount of a substance n Mole mol

SI Base Units

PrefixAbbreviatio

nPower of

Ten Meaning

kilo- k 103 1000

hecto- h 102 100

deka- da 101 10

Base Unit 100 1

deci- d 10-1 0.1

centi- c 10-2 0.01

milli- m 10-3 0.001

micro- 10-6 0.000 001

nano- n 10-9 0.000 000 001

pico- p 10-12 0.000 000 000 001

SI PrefixesKing Henry Died Belly-Up Drinking Chocolate Milk Under (a) Nice Picture.

We can form other necessary units from the seven SI base units.◦Examples: Speed = distance/time = m/s Area = length ∙ width = m2

Volume = l ∙ w ∙ h = m3

Use mL in chemistry 1L = 1000 mL = 1000 cm3 (1mL = 1cm3)

Derived Units

Why identify properties?◦They help us to learn more about substances.◦The more we know, the better we understand

the substance.

How are properties identified?◦By making observations about substances.

Properties

Physical vs. Chemical◦Physical Property – a property that can be

measured or observed without changing the chemical identity of the substance Examples: density, color, hardness, transparency

(how well light is able to pass through), melting point

◦Chemical Property – property that describes a substance’s ability to chemically interact with another substance Determined by trying to cause a chemical change Examples: flammability, reactivity with water, ability

to be oxidized

Properties

Density = mass divided by volume = m/V◦Units = g/mL or g/cm3

◦Found by measuring mass and volume Volume – use a ruler (l∙w∙h) or water

displacement (graduated cylinder)◦Graph results show density by slope of

line:

Can be used to identify substances.

Density

riserun

massvolume

= ∆y∆x

=

Lesson Essential Question (Section 3)

How do we classify matter?

Atom – smallest unit of an element that maintains the properties of that element.◦Ex: copper, nickel, boron, etc.

◦Almost all elements are made up of many individual atoms; but some are made of atoms that bond together: Br, I, N, Cl, H, O, F

Section 3: How is matter classified?

Pure substance – an element or compound that has definite chemical and physical properties (in other words has a chemical formula)◦Element – cannot be broken down into simpler

substances; contain only 1 kind of atom◦Molecule – 2 or more atoms bonded together that

retain the chemical & physical properties of that element or compound Elements: H2, O2, N2, Cl2, Br2, I2, F2 (same type of

atoms bond together) Compounds: H2O, CO2, HCl (different types of

atoms bond together)

Section 3: How is matter classified?

Allotrope: different form of an element*Examples: oxygen = O2, ozone = O3, diamond, graphite

Elements Cont.

carbon

graphite

diamond

Compound – substance made up of atoms of two or more different elements joined by chemical bonds.◦Can be further classified as ionic or

covalent to be discussed in later chapters)◦Examples: salt (NaCl), caffeine (C8H10N4O2)

Compounds

Mixture – combination of two or more substances that are NOT chemically combined◦Can vary in composition and properties◦Homogeneous – uniform throughout, often called a solution Examples: completely dissolved salt water, tea, stainless steel, maple syrup

◦Heterogeneous –not evenly mixed Examples: not completely dissolved salt

water, orange juice with pulp, chocolate chip cookie, granite, salad

Mixtures

Matter

Mixture

Homogeneous Heterogeneous

Pure Substance

ElementCompound

Graphic Organizer

separate physically

separate chemically

Helpful hints for classification:◦Homogeneous (solutions): cannot see

the individual substances that make it up (same uniform appearance & composition throughout).

◦Heterogeneous: consist of visibly different substances or states.

Mixtures Continued

Difference #1: Properties of compounds do not reflect

properties of elements making it up.◦ Properties are different from the elements.

Properties of mixtures do reflect properties of substances making them up.

Difference #2: Compounds always have definite

compositions of elements. Mixtures can have varying amounts of substances making them up.

Mixtures vs. Compounds