1. Chemistry: THE STUDY OF MATTER

2. So what is matter?

3. Matter Must have mass Must occupy space (have volume)
It is different from weight…..Why?
Must occupy space (have volume)
A measure of the quantity of matter (it is different from weight, which can be affected by gravity)
This volume can change depending on environmental conditions like pressure

4. Therefore: all matter has a measurable density
Density of a Substance = Mass
Volume

5. States of Matter Matter can exist in three basic states:
Solid (s), Liquid (l), Gas (g)
How are these states different from each other?

6. Can Matter be Destroyed?
Example:
When 400 grams of wood are burned only about 30 grams of ash remain.
Why does the matter weigh less?
What happened to the missing matter?

7. Law of Conservation of Matter
Matter cannot be created or destroyed
This was a revolutionary idea up until the 1800’s
Ex: Burn a candle, thought part of the candle just disappeared and became nothing.
But if you burn it in a closed container you can see the mass doesn’t change as it burns.
Matter isn’t being lost but changing in form!

8. During reactions atoms are all still there, they just get rearranged

9. Chemical equations are “balanced” with coefficients to obey this law.

10. Basic Types of Matter

11. Elements Made of atoms of one specific type Have specific properties.
Cannot be broken down further by a chemical reaction

12. Examples of Elements

13. Elements and Their Symbols
Element symbols are composed of either one or two letters
If two letters, the second letter is written lower case.
Ex:
Write Cu for copper not CU
Why is this so important?

14. Just Read:
Usually it is pretty easy to match an element to its symbol (Ex: Neon = Ne)
Sometimes the symbol is derived from a Latin name for the element.
Ex: Au = gold (comes from Latin word aurum)

15. Some Tricky Elements Na = sodium K = potassium Fe = iron Cu = copper
Sb = antimony
Sn = tin
Pb = lead
Hg = mercury
W = tungstun
Au = gold
Ag = silver

16. Phases of Elements at STP
Gases:
H, He, Ne, Ar, Kr, Xe, Rn, N, O, F, Cl
Liquids:
Hg, Br
Solids:
All other elements are solids
Let’s make a note of these on our Periodic Tables!

17. Diatomic Elements Composed of two identical bonded atoms Who are they?
Note: Most elements are monoatomic in pure form.
Who are they?
Remember BrINClHOF
Let’s make a note of these on our Periodic Tables!

18. Compounds Two or more different elements bonded together
Ex: C6H12O6, NO2, CO2, NaCl
Note: Most elements in nature do not exist in their pure state, but in compounds.
Why? They are more “stable” that way.
The numbers written below the symbols are called “subscripts” and let us know about the number of each type of atom in the compound

19. Compounds have formulas that show the proportion of elements to each other.
Ex: Water is always H2O
This is called the “Law of Definite Proportions”
Ex: H2O always has 2
hydrogen and one
oxygen atom in it

21. Compounds have different properties than the elements
they are composed of.
Ex:
Sodium (Na) Toxic metal
Chlorine (Cl) Toxic gas
Sodium Chloride (NaCl)
White edible crystal

22. Focus Question What makes atoms of one element different from another?

23. Atomic Basics Atoms consist of three basic parts. Protons Neutrons
Electrons

24. Fill in Chart: Particle Charge Mass Location Symbol Proton Neutron
Electron

25. Atomic Number: Tells us the number of protons in nucleus
It is unique for each element

26. Atomic Charge Atoms are neutral particles
Number of electrons (-) = number of protons(+)
How many electrons does an atom of carbon have?

27. Nuclear Charge Nuclear Charge: What is the Nuclear Charge?
the charge on the nucleus of the atom.
(+) positive charge = to number of protons
What is the Nuclear Charge?
What is the Atomic Number?
What is this Element?

28. Ionic Charge Ions: atoms with a charge Protons don’t equal electrons!!
Atom has gained or lost electrons
Gain electrons: become (-) ion
Lose electrons: become (+) ion
P = 9
E = 10
What is the element? What is it’s ionic charge?

29. Ionic Charge Practice
Try a few for practice…

30. Finding the Atom’s Mass
Mass Number:
Sum of the number of protons + neutrons
Each has a mass of 1 amu. (atomic mass unit)
Ex: P = 23 N = 21
What is the Atomic Mass Number?
What is this element?

32. Isotopes
Isotopes: atoms of the same element with different atomic mass.
Same # protons
Different # neutrons
Ex: Carbon-12, Carbon-13, Carbon-14
How many protons?
How many neutrons?

33. Average Atomic Mass: Atomic mass you see on periodic table
Represents the average mass of all the isotopes of an element in a typical sample.
Based upon abundance of each isotope and their mass

34. Calculating Average Atomic Mass
Mass of each isotope x abundance (change % abundance to decimal)
Add together answers
Ex: Chlorine

36. Crash Course Kids: What is Matter?
Crash Course: Atomic Basics