CH. 3 - ATOMIC STRUCTURE

The Atom: From Philosophical Idea to Scientific Theory OBJECTIVES EXPLAIN THE LAW OF CONSERVATION OF MASS, THE LAW OF DEFINITE PROPORTIONS, AND THE LAW OF MULTIPLE PROPORTIONS. SUMMARIZE THE FIVE ESSENTIAL POINTS OF DALTON’S ATOMIC THEORY. EXPLAIN THE RELATIONSHIP BETWEEN DALTON’S ATOMIC THEORY AND THE LAW OF CONSERVATION OF MASS, THE LAW OF DEFINITE PROPORTIONS, AND THE LAW OF MULTIPLE PROPORTIONS.

FOUNDATIONS OF ATOMIC THEORY THE TRANSFORMATION OF A SUBSTANCE OR SUBSTANCES INTO ONE OR MORE NEW SUBSTANCES IS KNOWN AS A CHEMICAL REACTION. LAW OF CONSERVATION OF MASS: MASS IS NEITHER CREATED NOR DESTROYED DURING ORDINARY CHEMICAL REACTIONS OR PHYSICAL CHANGES Chapter 3

Click below to watch the Visual Concept. Visual Concept Chapter 3 The Atom: From Philosophical Idea to Scientific Theory LAW OF CONSERVATION OF MASS

FOUNDATIONS OF ATOMIC THEORY, CONTINUED LAW OF MULTIPLE PROPORTIONS: IF TWO OR MORE DIFFERENT COMPOUNDS ARE COMPOSED OF THE SAME TWO ELEMENTS, THEN THE RATIO OF THE MASSES OF THE SECOND ELEMENT COMBINED WITH A CERTAIN MASS OF THE FIRST ELEMENT IS ALWAYS A RATIO OF SMALL WHOLE NUMBERS Chapter 3

Click below to watch the Visual Concept. Visual Concept Chapter 3 LAW OF MULTIPLE PROPORTIONS

FOUNDATIONS OF ATOMIC THEORY, CONTINUED LAW OF DEFINITE PROPORTIONS: A CHEMICAL COMPOUND CONTAINS THE SAME ELEMENTS IN EXACTLY THE SAME PROPORTIONS BY MASS REGARDLESS OF THE SIZE OF THE SAMPLE OR SOURCE OF THE COMPOUND

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DALTON’S ATOMIC THEORY ALL MATTER IS COMPOSED OF EXTREMELY SMALL PARTICLES CALLED ATOMS. ATOMS OF A GIVEN ELEMENT ARE IDENTICAL IN SIZE, MASS, AND OTHER PROPERTIES; ATOMS OF DIFFERENT ELEMENTS DIFFER IN SIZE, MASS, AND OTHER PROPERTIES. ATOMS CANNOT BE SUBDIVIDED, CREATED, OR DESTROYED. ATOMS OF DIFFERENT ELEMENTS COMBINE IN SIMPLE WHOLE- NUMBER RATIOS TO FORM CHEMICAL COMPOUNDS. IN CHEMICAL REACTIONS, ATOMS ARE COMBINED, SEPARATED, OR REARRANGED. Chapter 3

MODERN ATOMIC THEORY SOME IMPORTANT CONCEPTS REMAIN UNCHANGED. ALL MATTER IS COMPOSED OF ATOMS. ATOMS OF ANY ONE ELEMENT DIFFER IN PROPERTIES FROM ATOMS OF ANOTHER ELEMENT. NOT ALL ASPECTS OF DALTON’S ATOMIC THEORY HAVE PROVEN TO BE CORRECT. WE NOW KNOW THAT: ATOMS ARE DIVISIBLE INTO EVEN SMALLER PARTICLES. A GIVEN ELEMENT CAN HAVE ATOMS WITH DIFFERENT MASSES. Chapter 3

Review ???? DAY 2

THE STRUCTURE OF THE ATOM AN ATOM IS THE SMALLEST PARTICLE OF AN ELEMENT THAT RETAINS THE CHEMICAL PROPERTIES OF THAT ELEMENT. THE NUCLEUS IS A VERY SMALL REGION LOCATED AT THE CENTER OF AN ATOM. THE NUCLEUS IS MADE UP OF AT LEAST ONE POSITIVELY CHARGED PARTICLE CALLED A PROTON AND USUALLY ONE OR MORE NEUTRAL PARTICLES CALLED NEUTRONS. Chapter 3 THE NUCLEI OF ATOMS OF DIFFERENT ELEMENTS DIFFER IN THEIR NUMBER OF PROTONS THUS, THE NUMBER OF PROTONS DETERMINES THAT ATOM’S IDENTITY.

FORCES IN THE NUCLEUS WHEN TWO PROTONS ARE EXTREMELY CLOSE TO EACH OTHER, THERE IS A STRONG ATTRACTION BETWEEN THEM. A SIMILAR ATTRACTION EXISTS WHEN NEUTRONS ARE VERY CLOSE TO EACH OTHER OR WHEN PROTONS AND NEUTRONS ARE VERY CLOSE TOGETHER. THE SHORT-RANGE PROTON-NEUTRON, PROTON-PROTON, AND NEUTRON-NEUTRON FORCES THAT HOLD THE NUCLEAR PARTICLES TOGETHER ARE REFERRED TO AS NUCLEAR FORCES. Chapter 3

THE STRUCTURE OF THE ATOM, CONTINUED SURROUNDING THE NUCLEUS IS A REGION OCCUPIED BY NEGATIVELY CHARGED PARTICLES CALLED ELECTRONS PROTONS, NEUTRONS, AND ELECTRONS ARE OFTEN REFERRED TO AS SUBATOMIC PARTICLES. MOST OF THE ATOM IS EMPTY Chapter 3 Atoms are electrically neutral because they contain equal numbers of protons and electrons.

PROPERTIES OF SUBATOMIC PARTICLES Chapter 3

THE SIZES OF ATOMS THE RADIUS OF AN ATOM IS THE DISTANCE FROM THE CENTER OF THE NUCLEUS TO THE OUTER PORTION OF ITS ELECTRON CLOUD. BECAUSE ATOMIC RADII ARE SO SMALL, THEY ARE EXPRESSED USING A UNIT THAT IS MORE CONVENIENT FOR THE SIZES OF ATOMS. THIS UNIT IS THE PICOMETER, PM. Chapter 3

WHAT IS THE CHARGE OF A NEUTRON? MOST OF AN ATOM IS ___________ WHERE ARE ELECTRONS FOUND? WHAT IS THE NUCLEUS OF AN ATOM MADE UP OF? A MOLECULE OF CARBON MONOXIDE, CO, HAS ONE ATOM OF OXYGEN WHILE A MOLECULE OF CARBON DIOXIDE, CO 2, HAS TWO. IN A SAMPLE OF CO CONTAINING 1 G OF CARBON, 1.33 G OF OXYGEN WILL COMBINE WITH THE CARBON TO FORM THE MOLECULE. WHAT IS THE MASS OF OXYGEN IN A SAMPLE OF CO 2 CONTAINING 1 G OF CARBON? A.1.33 GB.3.0 G C.2.66 GD.0.0 G Review ????

ATOMIC NUMBER ATOMS OF DIFFERENT ELEMENTS HAVE DIFFERENT NUMBERS OF PROTONS. ATOMS OF THE SAME ELEMENT ALL HAVE THE SAME NUMBER OF PROTONS. THE ATOMIC NUMBER OF AN ELEMENT IS THE NUMBER OF PROTONS OF EACH ATOM OF THAT ELEMENT. Chapter 3

MASS NUMBER MASS # = PROTONS + NEUTRONS  always a whole number  NOT on the Periodic Table! Publishing Company, Inc.

ISOTOPES ATOMS OF THE SAME ELEMENT WITH DIFFERENT MASS NUMBERS. Mass # Atomic #  Nuclear symbol:  Hyphen notation: carbon-12

ISOTOPES C. Johannesson © Addison-Wesley Publishing Company, Inc.

ISOTOPES CHLORINE-37 ATOMIC #: MASS #: # OF PROTONS: # OF ELECTRONS: # OF NEUTRONS:

AVERAGE ATOMIC MASS WEIGHTED AVERAGE OF ALL ISOTOPES ON THE PERIODIC TABLE ROUND TO 2 DECIMAL PLACES Avg. Atomic Mass

Avg. Atomic Mass AVERAGE ATOMIC MASS EX: CALCULATE THE AVG. ATOMIC MASS OF OXYGEN IF ITS ABUNDANCE IN NATURE IS 99.76% 16 O, 0.04% 17 O, AND 0.20% 18 O amu

AVERAGE ATOMIC MASS EX: FIND CHLORINE’S AVERAGE ATOMIC MASS IF APPROXIMATELY 8 OF EVERY 10 ATOMS ARE CHLORINE-35 AND 2 ARE CHLORINE-37. Avg. Atomic Mass amu

CH 3- THE MOLE COUNTING ATOMS

WHAT IS THE MOLE? A COUNTING NUMBER (LIKE A DOZEN) DESCRIBES THE NUMBER OF PARTICLES AVOGADRO’S NUMBER (N A ) 1 MOL = 6.02  ITEMS A large amount!!!!

n 1 mole of hockey pucks would equal the mass of the moon! n 1 mole of basketballs would fill a bag the size of the earth! 1 MOLE OF PENNIES WOULD COVER THE EARTH 1/4 MILE DEEP!

Click below to watch the Visual Concept. Visual Concept Chapter 3 THE MOLE

MOLAR MASS MASS OF 1 MOLE OF AN ELEMENT OR COMPOUND. - MOLAR MASS EQUAL TO ATOMIC MASS UNITS PER ATOM (AMU) FOUND ON PERIODIC TABLE WRITTEN IN UNITS GRAMS PER MOLE (G/MOL)

MOLAR MASS EXAMPLES CARBON ALUMINUM ZINC g/mol g/mol g/mol

MOLAR MASS EXAMPLES WATER SODIUM CHLORIDE H2OH2O  2(1.01) = g/mol  NaCl  = g/mol

MOLAR MASS EXAMPLES SODIUM BICARBONATE SUCROSE  NaHCO 3  (16.00) = g/mol  C 12 H 22 O 11  12(12.01) + 22(1.01) + 11(16.00) = g/mol

Click below to watch the Visual Concept. Visual Concept Chapter 3 AVOGADRO’S NUMBER

MOLAR CONVERSIONS molar mass (g/mol) MASS IN GRAMS MOLES NUMBER OF Atoms/molecule s 6.02  (atoms/mol)

SOLVING MOLE PROBLEMS Chapter 3

MOLAR CONVERSION EXAMPLES HOW MANY MOLES OF CARBON ARE IN 26 G OF CARBON? 26 g C 1 mol C g C = 2.2 mol C

WHAT IS THE MASS IN GRAMS OF 3.50 MOL OF THE ELEMENT COPPER, CU? Chapter 3 MOLAR CONVERSION EXAMPLES

THE MOLAR MASS OF COPPER FROM THE PERIODIC TABLE IS ROUNDED TO G/MOL. Chapter 3

MOLAR CONVERSION EXAMPLES HOW MANY GRAMS OF CARBON ARE IN 4.0 MOLES OF CARBON? 4.0 mol C g C 1 mol C = 48 g C

MOLAR CONVERSION EXAMPLES HOW MANY MOLECULES ARE IN 2.50 MOLES OF C 12 H 22 O 11 ? 2.50 mol 6.02  molecules 1 mol = 1.51  molecules C 12 H 22 O 11

MOLAR CONVERSION EXAMPLES FIND THE MASS OF 2.1  MOLECULES OF NAHCO  molecules 1 mol 6.02  molecules = 290 g NaHCO g 1 mol