December 15, 2016 Today’s Schedule: Today you will need: Q/ A Go over Matter worksheet Notes for Particle Theory Today you will need: Pen/ Pencil Notebook/ Paper

Q/A How can we tell if something undergoes a chemical change? Something undergoes a chemical change if: Heat or Light is given off If there is a colour change If a precipitate is formed If it can not be reversed If gas is created

Models of Matter- The Particle Theory Section 2.1

Remember…… Matter is anything that has mass and takes up space. Models are used to try to describe what matter is. One model is the particle theory.

The Particle Theory More than 2000 years ago in Greece, a philosopher named Democritus suggested that matter was made up of tiny particles. He thought that if you cut a substance into smaller and smaller pieces, you would eventually come to the smallest possible particle. He called this particle the atom.

Democritus http://www.brainpop.com/science/matterandchemistry/atoms/

The Particle Theory There are 4 basic principles to the particle All matter is made up of tiny particles All particles of one substance are the same. Different substances are made of different particles.

The particles are always moving The particles are always moving. Particles at a higher temperature move faster than particles at a lower temperature. There are attractive forces between the particles. These forces are stronger when the particles are closer together.

Pure Substances and Mixtures There are 2 categories of substances: pure substances and mixtures. A pure substance contains only one kind of particle. Ex. A piece of aluminum foil contains only aluminum particles.

Pure Substances Pure substances can be broken down into two categories: elements and compounds. Elements are pure substances that cannot be broken down into simpler substances. They contain one kind of atom. Ex. Hydrogen, gold, silver.

Pure Substances Compounds are pure substances that contain two or more different elements chemically united in fixed proportions. They contain more than one kind of atom. Ex. Water, salt.

Mixtures A mixture contains at least two different pure substances, or two different types of particles. When we drink a glass of milk or eat a cookie, we are consuming a mixture.

Mixtures Mixtures can be broken down into three categories: solutions, heterogeneous or homogeneous mixtures. Solutions are formed when a solute dissolves in a solvent. Ex. Kool-aid is a solute and water is the solvent.

http://www.brainpop.com/science/matterandchemistry/compoundsandmixtures/

The properties of a solution are: the solute dissolves in the solvent Transparent Does not settle on standing Homogeneous- uniform composition throughout

Mechanical mixtures. Properties of mechanical mixtures include: When two or more different materials are mixed together but are visibly not whole. Ex: Cereal, stones on a beach, or a pizza. They can also be called a heterogeneous mixtures.

Heterogeneous Mixtures: have different parts that can mechanically be separated from the rest. From the next slide, try to name all the components found in this mechanical/ heterogeneous mixture.

From the video, how can we know for certain that the mixture was a mechanical mixture?

What is it?

Sugar that we buy at the store is a homogeneous mixture, you can not tell the difference between the components. Other examples ?

What is it?

Seeds are an example of a heterogeneous or mechanical mixture Seeds are an example of a heterogeneous or mechanical mixture. We know this because when we look at it, we can see the different components. Other examples ?

What is it ?

Gold is an element pure substance because it contains only one type of atom and can not be broken down.

What is it?

Water is a compound pure substance because it’s made up of two elements, combined in a fixed amount, 2 hydrogen and 1 oxygen.

What is it?

Grape juice is a homogeneous solution Grape juice is a homogeneous solution. It has a uniform composition throughout and appears to be only one substance. It also doesn’t settle.

Q/ A What are the differences between a homogeneous mixture and a heterogeneous mixture ?

Homogeneous mixture has a uniform composition throughout and you can’t separate the parts from the whole. Heterogeneous mixtures you can see the different components and can mechanically separate them.

Handout In this handout you have to determine whether something is a heterogeneous or homogeneous mixture. The second part asks you to determine whether something is an element, a compound, a mixture or a solution. Work quietly at your desks. You may listen to your ipod or mp3 player softly !

Q/A What would be: A substance that had only one type of atom? A substance that had two or more atoms chemically bonded in a fixed ratio? A mixture that you could not separate the parts from the whole?

An element ex: Zn = Zinc A Compound ex: NaCl= Salt Homogeneous Mixture ex: milk

Classwork pg-44-47/ Notes 1) Draw a diagram to show the difference between A) a pure substance and a mixture B) a solution and heterogeneous mixture Complete the following table 2) Question Term Definition Example Element Compound Mixture Atom Molecule `

4) From the following, decide if each is a pure substance element or compound. Explain! A) A clear, colourless liquid that can be split into two gases with different properties. B) A yellow solid that always has the same properties and cannot be broken down. C) A colourless gas that burns to produce carbon dioxide and water.

Answers Type Definition Example Element Only has one C= Carbon type of atom that cannot be broken down. Compound Is made up of two or H20 more elements that can be seperated or broken down. Mixture Contains two or more Milk/ Pizza particles that are not chemically bonded. Atom The smallest, indivisible H= Hydrogen part of a substance. Molecule When atoms join in fixed H2O2= combinations Peroxide

3) Give examples of two molecules that are made from the same types of atoms.

Compound- It can be split into two gases with different properties. Element- it always has the same properties and cannot be broken down. Compound- When the gas burns, two new substances are produced.

Chemical Symbols and Formulas 2.7

Chemical Symbols Mission: To devise a system of symbols to represent elements. Note: These symbols should be easy to differentiate from one another but shouldn’t look like those found on the periodic table. Materials: Pen/Pencil/Markers White Paper Glue or Tape Time Limit- 20 Minutes

Chemical Symbols Since the middle ages, scientists have been using symbols to represent chemicals. These were called Alchemists’ Symbols.

John Dalton used circles, letters and designs in them during the 1800’s. Most scientists found these confusing to use. Can you see why?

Dalton’s Symbols

Today’s Symbols Today, instead of using drawings and designs, we use chemical symbols that are abbreviations of the name of an element. Scientists have organized them in a way that they are standardized around the world.

Origins of Names Where do you think the name Hydrogen came from ? From the Greek word “water former”. Why is this a good name ?

Where did you think the name Mercury came from ? The symbol for Mercury, Hg, comes from the latin word hydrargyrum for liquid silver. Why do you think that is ?