Transcript File

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
• Observation and Inference
BUILDING SCIENTIFIC
KNOWLEDGE
• 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
Electrons
Protons
Neutrons
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
Symbol
Charge
Location
Atomic Mass
Proton
p
+1
Nucleus
1
Electron
e-
-1
Orbits Around
Nucleus
0.0001
Neutron
n
0
Nucleus
1
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 93-117: 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, 13-18
• 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
Mass Number:
M
Atomic Number:
P
Z
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