The Nature of Matter

Matter Anything that has mass and takes up

space Substance- single kind of matter that has

a specific make-up and specific properties-Example: Salt or sugar-Non-Example: Muffin batter (the ingredients can vary)

DESCRIBING MATTER (Notes 2-1)

Physical Properties of Matter Can be observed without changing into

another substance Examples: Freezing point, melting point,

density, texture, color, flexibility, solubility in water

Chemical Properties of Matter Ability to change into a different

substance Examples: flammability, rusting,

tarnishing, rising of bread in baking process

Elements Pure substances that cannot be broken down into

any other substance Simplest substances Is identified by its specific physical and chemical

properties Examples: Carbon, Oxygen, Gold, Silver,

Aluminum

Atoms Basic particle that makes up all elements Having different atoms gives elements their

unique properties Atoms have a nucleus made up of positively

charged protons and neutrally charged neutrons, and they are surrounded by a cloud of negatively charged electrons

Modeling an Atom Pencil “lead” is made of mostly graphite, a

form of carbon. Two ways to model atoms used in this presentation are shown here for carbon.

Chemical Bonds and Molecules

Atoms bond, or combine, by chemical bonds (a force of attraction between the electrons of 2 or more atoms)

Often form molecules- groups of 2 or more atoms held together by chemical bonds

Modeling Molecules Examples: H2O, O2, CO2

Compounds Pure substance made up of 2 or more elements chemically

combined in a set ratio Represented by a chemical formula which shows the

elements in the compound and the ratio of atoms When elements combine to form compounds, they have

unique properties from those of the uncombined elements-Example: Hydrogen alone is a very combustible gas, Oxygen alone is a major supporter of combustibility, but when combined in the set 2:1 ratio H2O, they put out fires!

Mixtures Made up of 2 or more substances that are not chemically combined Examples: Air, Soil, Salt water Differ from compounds because they do not have to have a set ratio,

and each substance in mixture keeps its individual properties

Two Types, Heterogeneous and Homogeneous: Hetero = different Can see different parts of mixture

Examples: Soil, Salad Homo = same * Can’t see different parts of mixture, evenly mixed

* Examples: Sugar/water solution, Air

Separating Mixtures Compounds are hard to separate Mixtures are easy to separate since each

component keeps its own properties Look at figure 10 on page 66, it shows

different ways to separate a mixture including using a magnet, filtering, distilling, and evaporating

Physical Changes Alters form or appearance

of matter but does NOT change matter into a different substance

Examples: -Changes of state (solid to liquid, or liquid to gas, etc.) -Changes in shape or form (dissolving, chopping, cutting, bending, breaking, etc)

Changes in Matter (Notes 2-2)

Chemical Changes• A change in matter that

produces one or more new substances

• Chemical change = chemical reaction

• New substances have properties different from original substances

• Examples: -burning of natural gas on gas stove (combustion) -rusting (oxidation)

Chemical Change

Law of Conservation of Matter

Matter is neither created nor destroyed in any physical or chemical change. No mass is lost because during a chemical change, atoms are not lost or gained, just rearranged.

• Conserving Matter: The idea of atoms explains the law of conservation of matter. For every molecule of methane that burns, two molecules of oxygen are used. The atoms are rearranged in the reaction, but they do not disappear.

ENERGYENERGY Who Who

remembers remembers the definition the definition of energy?of energy?

The ability to The ability to do WORK!do WORK!

Energy and MatterEnergy and Matter (Notes 2-3)(Notes 2-3)

All chemical and physical changes All chemical and physical changes include a change in energyinclude a change in energy

Law of Law of Conservation of Conservation of EnergyEnergy Energy is neither created nor Energy is neither created nor

destroyeddestroyed It is only transformed (changed It is only transformed (changed

from one form to another)from one form to another)

Forms of EnergyForms of Energy

Potential Vs KineticPotential Vs Kinetic

Energy waiting Energy waiting to be usedto be used

Ex: Food you eatEx: Food you eat

Energy of Energy of Motion Motion (Energy (Energy being used)being used)

Ex: You taking Ex: You taking notes! notes!

POTENTIAL ENERGY:POTENTIAL ENERGY: KINETIC ENERGY:KINETIC ENERGY:

Transforming Energy Transforming Energy Example 1:Example 1:

BurningBurning-Chemical change -Chemical change that transforms that transforms chemical energy chemical energy and releases it as and releases it as thermal energy thermal energy (heat) and (heat) and electromagnetic electromagnetic energy (light)energy (light)

Transforming Energy Transforming Energy Example 2:Example 2:

PhotosynthesisPhotosynthesis-Plants transform -Plants transform electromagnetic electromagnetic energy from the energy from the sun into chemical sun into chemical energy (sugar for energy (sugar for plants)plants)

Transforming Energy Transforming Energy Example 3:Example 3:

You Try!You Try! What energy What energy

transformations transformations occur when you occur when you ride a bike?ride a bike?

There is potential There is potential energy in the food you energy in the food you eat.eat.

Your cells transform Your cells transform food into chemical food into chemical energy your body can energy your body can use.use.

Chemical energy is Chemical energy is transformed to kinetic transformed to kinetic energy of moving energy of moving muscles and thermal muscles and thermal energy given off as energy given off as heat.heat.