1. Properties of Matter
Understanding our world and being able to use that knowledge to help us means describing things and understanding how they behave.
What are the ways and words we can use to describe “stuff?”
How does “stuff” behave? What does it do when we make changes to it?
Is the “stuff” one thing (pure) or more than one thing (mixture)?
Once we make changes to stuff what are its new characteristics? Can we change new stuff back into the old stuff?”
Properties are the characteristics and behaviors we use to describe matter!

2. Properties of Matter - physical state1
Matter: anything that has mass (weighs something) & takes up space (has volume). Matter has 3 forms or physical states

3. Physical & Chemical Properties2
Properties can be broken down into two types - physical and chemical properties. What’s the difference?
Chemical: properties of a pure substance that describe its ability to combine with or change into a new substance. Examples:
Physical: properties of a pure substance, we can see without changing it into a new substance. Examples include:
Flammability
Reactivity
physical state: solid, liquid, gas
color
shape
mass
texture
melting & boiling point
density
solubility in water

4. Properties - Pure Substances3
Matter can either be found in nature as a pure substance or a mixture. What does it mean to be pure?
Pure substance - a substance that contains a single type of matter. When the substance is pure, it has a unique set of properties
Example: pure water contains ONLY molecules of water (H2O) and NOTHING else!! When water is pure it has the following properites:
a defined melting point (0 °C)
no color
a defined boiling point (100 °C)
no taste
a defined density (1 g/mL)
does not burn
Pure substances have characteristic properties which we can use to identify the substance…
…imagine you had a colorless liquid that boiled at 100° C, melted at 0° C, and had a density of 1 g/mL, you could say it is most likely water!!

5. Properties of Matter - Mixtures4
Mixture - two or more substances mixed together, but not chemically combined. Each component in a mixture keeps its individual properties.
Example: salt water contains water molecules (H2O) and sodium chloride (NaCl) molecules.
The mixture will behave differently than the two materials separate. Salt water will have a different boiling point than pure water!
Because the parts of a mixture are not chemically combined, the parts can often be separated (purified) into their pure forms by taking advantage of their properties.
Salt can be separated from water by distilling the water (heating it to boiling), leaving behind salt, collecting water pure as it condenses.
If you separate salt from water, the two substances will have the same properties as they would before you mixed the two.

6. Solubility and Solutions5
Some substances are able to dissolve other materials. If you put sugar into water, the water will dissolve the sugar. The sugar will soon disappear (sugar molecules are dissolved in the water)…
Solubility - the property describing how much of a material can be dissolved.
Salt has a high solubility in water. We can dissolve a lot of salt in water.
Pepper is not soluble in water. We can say pepper is insoluble in water.
Solution - a special type of mixture where one of the components mixes evenly throughout (dissolves) so that you can’t visibly see one of the parts.
Dissolving a substance is an example of a phyiscal change. The substance is STILL THERE, and hasn’t been changed into anything new!

7. Mixtures - In mixtures you see more than one Thing (phase)4
Mixture -
- If you separate salt from salt water, the water will have the same properties as it would before you mixed the two
- BUT… The mixture as a whole can behave differently (salt water will have a different boiling point than pure water)
- A mixture containing stuff not soluble in water could be filtered, leaving behind the stuff that doesn’t dissolve (sand & water)
- In mixtures you see more than one Thing (phase)
Solution -
Components in mixtures can often be separated (purified) into their pure forms by taking advantage of their properties
- Salt can be separated from water by distilling the water (heating it to boiling), leaving behind salt, collecting water pure as it condenses
- In a solution you see only one thing (phase)

8. Let’s play Solution or Not Solution!!
Distilled water water?
Sprite?
Pure substance!
only water - pure
Solution
Dissolved Ingredients including gas (CO2)
Salt?
The ocean?
Mixture!
mixture of salts, fish, seaweed…
Pure substance!
Sodium Chloride - pure

9. Density 6 Density is the ratio of the mass of an object to its volume.
Density is determined by measuring the mass of an object, and measuring the volume, then dividing the two. Mass is measured in grams (g), volume in milliliters (mL).
Density (D) = Mass g (M)
Volume mL (V)
Density is a characteristic property of pure substances; it will always be the same under a given set of conditions. Example: density of water at 25 °C is 1 g/mL.
Objects with lower densities tend to float (cork floats in water). Objects with higher densities tend to sink (oil floats because it is less dense).
Oil floating on top of water
Cork in water

10. Density 7 Lots of things affect density…
Temperature: cool air sinks, warm air rises
Cold water sinks, warm water rises, creating layers of water
Water with salts dissolved in them tend to be more dense than pure water. So, salt water (for example, in the ocean) will sink to the bottom while fresh water will float on top.

11. Density 8
The Dead Sea in Israel has such a high concentration of salt (amount dissolved in water) that people can float in the water.
Ocean water is ~3.5% salt. The Dead Sea has a salinity of ~34%!!!!

12. Molecules and Compounds9
Let’s try to describe matter in some more detail…
Matter
Pure substances: (water, salt, sugar)
Mixtures: (soil, air)
Compounds, Molecules & Elements
can be broken down further into
Molecule - a single unit of a pure substance, chemically combined (bonded) in a defined ratio.
Examples: water (H2O), hydrogen peroxide (H2O2), sodium chloride (NaCl)
Compound - many molecules of the same pure substance. Example: a glass of water contains many millions of molecules of water.

13. Elements 10
Element - a pure substance consisting of a single type of atom
- each element has distinctive properties. Some are stable, and can be found by themselves in nature. Others are so reactive, they will only be found combined with other elements.
- elements can’t be broken down further and still keep their properties
- about 100 different elements
- elements identified by 1 or 2 letter symbols. Letters often are the first letters of the name of the element (Chlorine -> Cl)
- organized in a specific way into the Periodic Table of the Elements.

14. Periodic Table of the Elements11
The Periodic Table organizes elements into a set of patterns, arranged by increasing atomic number, invented by Russian chemist Dimitri Medeleev (1869)
Nonmetals: properties include poor conductors of heat & electricity, solids are brittle & dull
Metals: properties include malleability, ductility, good conductors of heat/electricity, magnetic
Metalloids: have both characteristics of metals and metalloids

15. Elements: Hydrogen & Oxygen12
You are probably familiar with certain elements…

16. Elements: Chlorine & Nitrogen13

17. Elements: Carbon & Sodium14

18. Elements: Iron & Aluminum15
Adding other metals (Nickle, Tungsten) to steel gives different properties.

19. Properties of Elements16
brittle, dull, not magnetic, not malleable
have poor conductivity - good insulators
many are gases, tend to be reactive
Nonmetals: Hydrogen (H2), Oxygen (O2), Carbon (C ), Chlorine (Cl2)
Metals: Sodium (Na), Iron (Fe), and Aluminum (Al)
Shininess, magnetic
malleability: ability of a substance to be molded/formed
conductivity: ability of a substance to transfer heat/electricity
Reactivity: willingness and ability to combine with other elements
- Many of the elements are so reactive that they are not found alone in nature. Wanna see how reactive?

20. Pure substances: (water, salt, sugar)
Describing Matter 17
Matter
Elements: pure substance with distinctive properties can’t be broken down further by physical or chemical means and retain their properties
Pure substances: (water, salt, sugar)
Mixtures: (soil, air)
Compounds, Molecules & Elements
can be broken down further into
are composed of
Atoms: smallest building block of which matter is composed

21. Structure of Atoms 18
Atoms: smallest building block of which matter is composed, when combined in specific ratios, they make the elements
Theory of atomic structure says that all atoms consist of:
Nucleus -
contains protons with a positive charge (+) - +
and neutrons (neutral, no charge)
Electrons -
particles with negative charge (-) orbiting nucleus in a “cloud”
An element is identified by the number of protons in its nucleus, called the atomic number.
An atom having 6 protons in its nucleus is a called a carbon atom

22. Combining Atoms 19
Atoms can combine to form a single molecule of a new substance. Remember, a molecule is a single unit of a substance, combined in defined ratios
Atoms in molecules are held together by attractive forces called bonds. Na
Sodium atom +
Chlorine atom Cl
1 Sodium chloride molecule Na Cl
reaction
Sodium chloride - inert (not reactive) colorless solid you can eat!
Sodium - very reactive metal +
Chlorine - toxic & reactive green gas
Compounds often have different properties than the elements that make them up!

23. Combining Atoms 20 Atoms combining in defined ratios 1 Water molecule
reaction H O
2 Hydrogen atoms H +
Oxygen atom O
Hydrogen - very light, flammable gas
Oxygen - colorless gas, explosive +
Water - needed by all life, can drink it
Again, compounds often have different properties than the elements that make them up!

24. Changes to Matter 21
Now that we have described matter and put it into different catagories, we can describe how matter changes…
Physical properties: characteristic of a pure substance that can be observed without changing it into another substance.
- water always has a density of 1 g/mL at 25° C
- at atmospheric pressure, water always melts at 0°C, and boils at 100°C
Physical changes: changes to a substance that can be observed without changing its identity. Examples…
- Change of state, which is easily reversed. For example, water freezes into ice, boils into water vapor, but it’s still water!
- Dissolving a substance into another substance. Salt dissolves in water, but they are not chemically combined. They can be separated (distillation)
Physical changes are sometimes hard to notice…

25. Chemical Changes 22
Chemical properties: a characteristic ability of a substance to change into another substance.
- Sodium metal is very reactive, never found alone in nature
- Examples of chemical properties: flammablility, reactivity (the desire of a substance to combine with and form new susbtances
Chemical changes: changes to a substance that results in a new substance forming.
Chemical changes are often much more obvious than physical changes
Color change
Light, heat, or energy released (burning)
Gases or solids form where there were none before

26. Chemical Changes 23

27. From Smallest to Largest24
Atoms - smallest building blocks of matter (e.g. an atom of Oxygen contains 16 protons)
Elements - many atoms of the same kind (e.g. Oxygen) O
Molecules - several atoms bonded together in a defined ratio to form a pure substance (e.g Oxygen atoms react with Hydrogen atoms to form a single molecule of water) H O
Compounds - many molecules of the same pure substance