2 Subatomic particles Relative mass Actual mass (g) Name Symbol Charge Electrone--11/18409.11 x 10-28Protonp++111.67 x 10-24Neutronn011.67 x 10-24
3 Counting the Pieces Atomic Number = number of protons in the nucleus # of protons determines kind of atom (since all protons are alike!)the same as the number of electrons in the neutral atom.Mass Number = the number of protons + neutrons.These account for most of mass
4 Counting the Pieces Protons: equal to atomic number Neutrons: Mass Number – Atomic NumberElectrons: In a neutral atom equal to atomic number
5 SymbolsContain the symbol of the element, the mass number and the atomic number.
6 SymbolsContain the symbol of the element, the mass number and the atomic number.MassnumberXAtomicnumber
7 F Symbols 19 9 Find the number of protons number of neutrons number of electronsAtomic numberMass Number19F9
8 Br Symbols 80 35 Find the number of protons number of neutrons number of electronsAtomic numberMass Number80Br35
9 Symbolsif an element has an atomic number of 34 and a mass number of 78 what is thenumber of protonsnumber of neutronsnumber of electronsComplete symbol
10 Symbols if an element has 91 protons and 140 neutrons what is the Atomic numberMass numbernumber of electronsComplete symbol
11 Symbols if an element has 78 electrons and 117 neutrons what is the Atomic numberMass numberNumber of protonsComplete symbol
12 What if Atoms Aren’t Neutral Ions: charged atoms resulting from the loss or gain of electrons
13 What if Atoms Aren’t Neutral Anion: negatively charged ion; result from gaining electronsTake the number of electrons in a neutral atom and add the absolute value of the chargeIdentify:Number of ProtonsNumber of NeutronsNumber of Electrons811-Br35
14 What if Atoms Aren’t Neutral Cation: positively charged ion; result from the loss of electronsTake the number of electrons in a neutral atom and subtract the value of the chargeIdentify:Number of ProtonsNumber of NeutronsNumber of Electrons27Al3+13
15 IsotopesAtoms of the same element can have different numbers of neutronsDifferent mass numbersCalled isotopes
16 Naming IsotopesWe can also put the mass number after the name of the element.carbon- 12carbon -14uranium-235
17 Atomic Mass How heavy is an atom of oxygen? There are different kinds of oxygen atomsWe are more concerned with average atomic massAverage atomic mass is based on abundance of each element in nature.We don’t use grams because the numbers would be too small
18 Measuring Atomic Mass Unit is the Atomic Mass Unit (amu) It is one twelfth the mass of a carbon- 12 atomEach isotope has its own atomic mass, thus we determine the average from percent abundance
20 Pure Substances Cannot be physically separated Every sample has the same characteristics and they can be used to identify a substance
21 Elements Are made up of ONE type of atom Atoms are the smallest unit of an element that maintains the chemical identity of that elementThey can be found on the Periodic TableExamples: Carbon, Nitrogen, Calcium
22 Compounds Can be broken down into simple stable substances Are made up of two or more types of atoms that are chemically bondedExamples: Water (H2O), sugar (C12H22O11)
23 MixturesA blend of two or more kinds of matter, each which retains its own identity and properties
24 Homogeneous Mixtures Have uniform composition Also known as SOLUTIONS Examples: salt water, tea
25 Solutions ALLOYS are solid solutions that contain at least 1 metal They are blended together so that they have more desirable propertiesSome alloys you may know are:Stainless Steel: iron, chromium, and zincBrass: zinc and copperBronze: tin and copperSterling Silver: copper and silver
26 Heterogeneous Mixtures Do not have uniform compositionYou can see the particles in themExamples:Sand on the beach (contains sand, shells, rocks, bugs, etc)Soil (contains dirt, rocks, worms, etc)Chicken Soup (contains water, chicken, veggies etc)
27 SuspensionsA heterogeneous mixture where the solid particles eventually settle out of solutionExamples:Muddy waterMixtures of two solidsPaint
28 Properties of MatterAll pure substances have characteristic propertiesProperties are used to distinguish between substancesProperties are also used to separate substances
29 Physical PropertiesA Physical Property is a characteristic that can be observed or measured without changing the composition of the substancePhysical properties describe the substance itselfExamplesPhysical StateColorMass, shape, lengthMagnetic properties
30 Chemical PropertiesA Chemical Property indicates how a substance will react with anotherChemical properties cannot be determined without changing the identity of the substanceExamples:Iron RustingSilver Tarnishing
31 Physical ChangesA Physical Change is a change in a substance that does not alter the substance’s identityExamples:GrindingCuttingMeltingBoiling
32 Chemical ChangesA change in which one or more substances are converted into different substances is called a Chemical ChangeSigns of a Chemical Change:Color ChangeGas is ReleasedTemperature ChangePrecipitate – Solid falls out of solutionSubstance Disappears
33 How Atoms CombineTwo or more atoms that are chemically combined make up a compoundThe combination results in a chemical bond, a force which holds elements together in a compound
34 Covalent BondsCovalent Bonds are formed when atoms in a compound share electronsMolecule – two or more atoms held together by a covalent bondUsually occurs between nonmetals
36 Ions An atom that has gained or lost an electron is called an ion. Multiple atoms can combine to form an ion – called a Polyatomic IonSilicate (SiO44-) and Carbonate (CO32-) are important in forming materials at Earth’s Surface
37 Ionic Bonding Positive and negative ions attract each other Ionic Bonds occur when oppositely charged ions form a compoundUsually consist of 1 metal and 1 nonmetalPositive ion written first in chemical formula (NaCl)Ionic compounds have a neutral charge
41 Democritus Democritus added: Matter is composed of atoms which move through empty spaceAtoms are solid, homogeneous, indestructible, and indivisibleDifferent atoms have different shapes and sizesThe size, shape, and movement of atoms determine their properties
42 Leading to the modern theory Late 1700’s - John Dalton- England.Teacher- summarized results of his experiments and those of others.Dalton’s Atomic TheoryCombined ideas of elements with that of atoms.Saw atoms as small solid spheres. Billiard Ball Model.
43 Dalton’s Atomic Theory All matter is made of tiny indivisible particles called atoms.Atoms of the same element are identical, those of atoms of different elements are different.Atoms of different elements combine in whole number ratios to form compounds.Chemical reactions involve the rearrangement of atoms. No new atoms are created or destroyed.
44 Law of Conservation of Mass The law of conservation of mass states that matter is neither created nor destroyed in chemical reactions
45 Discovery of the Electron J. J. Thomson - English physicist. 1897Made a piece of equipment called a cathode ray tube.It is a vacuum tube - all the air has been pumped out.
63 He ExpectedThe alpha particles to pass through without changing direction very much.Because…?…the positive charges were thought to be spread out evenly. Alone they were not enough to stop the alpha particles.
73 What are acids and bases? ACIDS BASESTASTE SOUR BITTERFEEL STINGS SLIPPERYREACTIONS YES / METAL NO / METALSCONDUCTS ELECTROLYTE ELECTROLYTERELEASES H OH-
74 HOW DO WE MEASURE ACIDS AND BASES? INDICATORSA SUBSTANCE THAT TURNS ONE COLOR IN AN ACIDIC SOLUTION AND ANOTHER COLOR IN A BASIC SOLUTIONSOME INDICATORS ARE:LITMUS: DYE THAT COMES FROM A LICHENPHENOLPHTHALEIN: INDICATES ONLY BASESUNIVERSAL INDICATOR:ACID, NEUTRALS, BASESCABBAGE JUICE:ACIDS, NEUTRAL, BASE
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