Chemistry: THE STUDY OF MATTER

So what is matter? So what is matter?

Matter Must have mass Must have mass It is different from weight…..Why? It is different from weight…..Why? Must occupy space (have volume) Must occupy space (have volume)

Matter Has Density Density of a Substance= Mass Density of a Substance= MassVolume See Reference Table S to compare density of elements

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

Can Matter be Destroyed? Example: When 400 grams of wood are burned only about 30 grams of ash remain. When 400 grams of wood are burned only about 30 grams of ash remain. What would you think? What would you think? What happened to the missing matter? What happened to the missing matter?

Law of Conservation of Matter Matter cannot be created or destroyed Matter cannot be created or destroyed Matter isn’t being lost but changing in form!

Atoms are all still there they just get rearranged Atoms are all still there they just get rearranged

Balanced chemical equations show the number of atoms stay the same during reactions and thus obey this law. Balanced chemical equations show the number of atoms stay the same during reactions and thus obey this law.

Basic Types of Matter: Elements vs. Compounds

Elements Made of atoms of one specific type Made of atoms of one specific type Cannot be broken down chemically Cannot be broken down chemically Have specific properties. Have specific properties.

Examples of Elements

Where Do We Get Elements? Obtained in nature in their pure state. Obtained in nature in their pure state.

Found combined with other elements in compounds Found combined with other elements in compounds

Man-made through nuclear bombardment reactions Man-made through nuclear bombardment reactions

Elements and Their Symbols Take Note Please! Take Note Please! Elements have either one or two letters when they are written as a symbol. Elements have either one or two letters when they are written as a symbol. If two letters, the second letter is written lower case. (Ex: Write Cu for copper not CU) If two letters, the second letter is written lower case. (Ex: Write Cu for copper not CU) Why is this so important? Why is this so important?

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

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

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

Diatomic Elements Most elements are monoatomic in pure form. Most elements are monoatomic in pure form. Some elements have two atoms joined (diatomic) Some elements have two atoms joined (diatomic) Who are they? Remember BrINClHOF Remember BrINClHOF Let’s make a note of these on our Periodic Tables! Let’s make a note of these on our Periodic Tables!

Compounds Two or more different elements bonded together chemically Two or more different elements bonded together chemically Ex: C 6 H 12 O 6, NO 2, CO 2, NaCl Note: Most elements in nature do not exist in their pure state, but in compounds. Note: Most elements in nature do not exist in their pure state, but in compounds. Why? Why?

Law of Definite Proportions Compounds have specific formulas that show the proportion of elements to each other. Compounds have specific formulas that show the proportion of elements to each other. Ex: Water is always H 2 O Ex: Water is always H 2 O A “mixture” has proportions that can vary A “mixture” has proportions that can vary Ex: salt water Ex: salt water

Getting New Properties Compounds have different chemical and physical properties than the elements that make them up. Compounds have different chemical and physical properties than the elements that make them up.

- Sodium (Na) Toxic metal - Chlorine (Cl) Toxic gas Sodium Chloride (NaCl) White edible crystal salt for my french fries!!

Focus Question What makes atoms of one element different from another? What makes atoms of one element different from another? What is inside its atoms… What is inside its atoms…

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

Fill in Chart: Fill in Chart: ParticleChargeMassLocationSymbol Proton Neutron Electron

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

Does an Atom Have a Charge? Atoms are neutral particles Atoms are neutral particles Number of electrons (-) = number of protons (+) Number of electrons (-) = number of protons (+) How many electrons does an atom of carbon have? How many electrons does an atom of carbon have?

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

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

Ionic Charge Practice Try a few for practice…

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

Isotopes Isotopes: atoms of the same element with different atomic mass. Isotopes: atoms of the same element with different atomic mass. Same # protons Same # protons Different # neutrons Different # neutrons Ex: Carbon-12, Carbon-14 (two isotopes of C) Ex: Carbon-12, Carbon-14 (two isotopes of C) How many protons? How many protons? How many neutrons? How many neutrons?

Average Atomic Mass Average Atomic Mass: Average Atomic Mass: The atomic mass you see on the periodic table The atomic mass you see on the periodic table Based upon abundance of isotope and its mass in an sample of the element Based upon abundance of isotope and its mass in an sample of the element

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