UNIT 1 – MATTER AND QUALITATIVE ANALYSIS

OBJECTIVES 1.To understand the difference between observation and inference 2.To understand the difference between theoretical and empirical knowledge 3.To explain the development of the atomic model 4.To describe the relationship between atomic number, atomic mass, and the different subatomic particles 5.To relate observations and inferences and describe real world examples

BUILDING SCIENTIFIC KNOWLEDGE Observation and Inference Observation: Statement that is based on what you see, hear, taste, touch and smell Inference: A judgment or opinion that is based on observations and/or conclusions Integral part of qualitative analysis When trying to identity matter, scientists firs observed the sample, then they infer based on their observations and comparing to known matter

TASK: THE BURNING CANDLE Materials: Candle, match, ruler, timer 1.Obtain a candle, match and watch glass 2.Light the candle ad drip some wax on the watch glass. Place the candle upright in the hot wax and secure it. 3.Observe the candle for 5 minutes a.Write down as many statements as possible about the burning candle b.Divide the statements into two categories: observations and inferences c.Compare the number of observations to the number of inferences

EXTENSION Provide ONE example of an observation and ONE example of an inference that could be stated by each of the following: A nurse examining a patient with a high fever A chef tasting a new recipe A paramedic arriving at the scene of an accident A firefighter sifting through the debris of a recently extinguished fire

EMPIRICAL AND THEORETICAL KNOWLEDGE Empirical Knowledge: knowledge coming directly from observations Theoretical Knowledge: knowledge based on ideas that are created explain observations Theory: an explanation of a large number of related observations

MODELS Model: representation of a theoretical concept Help to visualize a theory and suggest ways to test the theory

HOMEWORK Page 12: #1-3

EARLY ATOMIC MODELS (TEXT REF. 1.3) Atom: the smallest particle on an element that has all the chemical properties

DALTON’S ATOMIC THEORY (1803) All matter consists of definite particles called atoms Each element is made up of its own type of atom Atoms of different elements have different properties Atoms of two or more elements can combine in constant ratios to form new substances Atoms cannot be created, destroyed or subdivided in a chemical change

DALTON’S MODEL (BILLIARD BALLS)

SUBATOMIC PARTICLES - ELECTRONS 1897: J. J. Thomson used cathode ray tubes to examine gas discharge Observed: All gases emitted beams that behaved the same under magnets Inferred: There must be particles within all atoms that are the same and are negatively charged Later: names electrons

THOMSON’S MODEL “The Raisin Bun” model: + and – charges are mixed together Gave us electrons: Electrons are negatively charged Atoms can gain or lose electrons to form ions

RUTHERFORD’S EXPERIMENT

ANTICIPATED: Actual:

RUTHERFORD’S MODEL Protons Neutrons Electrons

EXPLANATION The atom is made of a dense core (nucleus) with positively charged protons and neutral neutrons Electrons orbit around the nucleus The number of protons determines the element’s identity The number of electrons equals the number of protons in NEUTRAL elements

ISOTOPES Elements with the same number of protons but a different number of neutrons are called isotopes Masses are averaged on most periodic tables Example: Carbon 6 proton; 6 electrons Most carbon atoms have 6 neutrons: Carbon-12 Some have 7 neutrons: Carbon-13 Some have 8 neutrons: Carbon-14

SUMMARY OF SUB-ATOMIC PARTICLES SymbolChargeLocationAtomic Mass Protonp+1Nucleus1 Electrone-e- Orbits Around Nucleus Neutronn0Nucleus1

THE PERIODIC TABLE: AN INTRODUCTION The Periodic Table is an incredibly useful tool that organizes all known elements into columns and rows according to their chemical and physical properties Elements 1-92: Elements that are found naturally on earth (except 43) Elements : Not stable, made in particle accelerators Group: columns Period: rows Metals are on the right; Non-metals are on the left; Metalloids are on the jagged line going down the left hand side

SOME SPECIFICS: Main Group Elements: Groups 1-2, Alkali Metals: Group 1 (extremely reactive metals) Alkaline Earth Metals: Group 2 Halogens: Group 17 (very reactive non-metals) Noble Gases: Group 18 (non-reactive gases) Transition Metals: Groups 3-12 Lanthanides: Top row of the bottom section Actinides: Bottom row of the bottom section

PERIODIC TABLES - ACTIVITY On the blank periodic table, colour code each section, label them Metals Non-metals Metalloids Alkali Metals Alkaline Metals Transition Metals Lanthanides/Actinides Halogens Noble Gases

PERIODIC TABLES Tell you a lot of information Elements in the same groups have similar bonding properties and reactivity patterns Elements in the same periods have similar sizes As you increase in number on the periodic table, you increase in atomic mass They often contain the following information: Atomic Number Atomic Mass Electronegativity Element Charges

DETERMINING #PROTONS, ELECTRONS, NEUTRONS Atomic Number (P): Number of Protons # p = # e - Atomic Mass (M): Number of Protons (P) + Number of Neutrons (N) M = P + N

EXAMPLE Determine the number of protons, neutrons and electrons in neutral a. Iron-56 b. Bismuth-209

ATOMIC SYMBOLS Z M P Atomic Number: Mass Number:

HOMEWORK: Page 15 #2,3,4,6 Worksheet: Protons, Neutron, and Electrons

I CAN: 1.Understand the difference between observation and inference 2.Understand the difference between theoretical and empirical knowledge 3.Explain the development of the atomic model 4.Describe the relationship between atomic number, atomic mass, and the different subatomic particles 5.Relate observations and inferences and describe real world examples

NEXT CLASS: Quiz: Observation/Inference, Theoretical/Empirical, Periodic Table, Atomic Models, Electrons/Protons/Neutrons Required: Name of Element for Element Assignment Topics: Electromagnetic Spectrum, Bohr’s Model, Chemical Bonding