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Changes in StateMelting: Solid ! Liquid
Freezing: Liquid ! Solid
Note: Melting Point = Freezing Point
Evaporation: Liquid ! Gas
Condensation: Gas ! Liquid
Sublimation: Solid ! Gas
Deposition: Gas ! Solid
5 Points of The Particle Theory of Matter
2. All particles have spaces between them
3. All particles of one pure substance are the same. Different substances are made up of different particles
5 Points of The Particle Theory of Matter4. The particles are always moving. The more energy
the particles have, the faster they move. 5. There are attractive forces between the particles.
The forces are stronger when the particles are closer together
The Particle Theory of Matter& Changes in State
• As energy is added to the particles, they move around more.
• Bonds between particles weaken
• When the particles can slide past each other, the substance is now a liquid
• When the particles are no longer bonded to each other and are flying around randomly, the substance is now a gas
THE HISTORY OF MATTER
Ancient Greek Philosophers• Did almost no
experimentation • Empedocles proposed
matter was composed of 4 elements
• Democritus suggested matter was made up of “atomos”, which means indivisible
• Socrates and Aristotle rejected Democritus’ ideas.
Alchemists• First to perform experiments • 3 main goals:
1. To change base metals into valuable ones (ex. Gold) 2. To find the substance that would give them eternal
life 3. To produce a universal solvent that would dissolve
all substances
Modern Chemists• Used scientific method & focused
on determining the properties and composition of pure substances
• Sir Francis Bacon one of the first to develop new knowledge from experimentation
• Boyle aimed to improve 4-element theory
• Lavoisier defined “element” and identified 23 different elements through measurement and observations
What is an atom?• The smallest particle of any
type of matter
• Shape: Spherical
• Size: 10-10 m
• Consists of: subatomic particles called nucleus, protons, neutrons, electrons
Skydome in Toronto = Atom Baseball = Nucleus Marbles inside baseball = Protons Mosquitoes buzzing around baseball = Electrons
Subatomic Particle
Symbol and Charge Mass Location
Proton p+ 1 amu nucleus
Neutron n 1 amu nucleus
Electron e- 1/1837 amu electron shell
Who discovered the atom?
• Democritus: “Atomos” • Dalton: All elements are
composed of atoms
What are the other models of atoms?
Dalton’s Model (1800’s)
• “Billiard ball” model • Atom is a solid, indivisible, indestructible sphere with no
subatomic particles • Each element is composed of 1 type of atom and is
characterized by the mass of its atoms • Joining of atoms of 2 or more elements = a compound • Atoms are not created or destroyed in a chemical change
Thomson’s Model (1904)• “Plum pudding” model • Discovered electrons & protons • Proposed atoms are spherical • Proposed electrons are embedded in sphere
Rutherford’s Model (1911)• Discovered existence of
the nucleus • Proposed nucleus is tiny,
dense and positive core of the atom
• Proposed protons are contained in nucleus
• Proposed nucleus is surrounded by empty space
• “Electron cloud”
Bohr’s Model (1913)• “Planetary” model • Placed electrons in
specific orbits around nucleus
• Electrons move around nucleus in circular paths called orbits
• Electrons more stable when at lower energy levels, closer to the nucleus
Quantum Model• The “wave” model • Explained more complex
atoms • Proposed it is impossible
to determine the exact location of an electron
• Shows how electrons move randomly in orbitals with varying energy levels
• Location of an electron is based on its energy
What is an element?•A pure substance that
cannot be broken down into simpler substances
•Made up of identical atoms
Naming Elements• Chemical symbol: Abbreviation of
the name of the element
• A single letter symbol is always capitalized. Ex. Carbon = C
• The first letter of a 2-letter symbol is always capitalized, while the second letter is lower case. Ex. Aluminum = Al
Where do the names come from?
• In Latin… • Gold = Aurum • Silver = Argentum • Lead = Plumbum
• Einsteinium = Es
What information does the Period Table give us?
• Element... • Name • Symbol • Atomic mass • Atomic number
What information does the Period Table give us?
• Atomic mass = • The average mass of
an atom of the element
• The sum of the number of protons and neutrons in the nucleus of an atom
What information does the Period Table give us?
• Atomic number = • The number of
protons in the nucleus of an atom.
What information does the Periodic Table give us?
• # Electrons = Atomic #
• # Protons = Atomic # • # Neutrons = Atomic Mass – Atomic #
Atomic Mass – proton # *Note:
If number of protons are known, you can identify the element since
atomic # = # of protons.
Atomic Notation
• Atomic mass in upper left, superscript
• Chemical Symbol • Atomic number in
lower left, subscript
Ti47.87
22
Bohr Models
• The center contains the number of protons and neutrons
• The outer “shells” consist of electrons
• Exact position of electrons in shells is not important.
• Electrons should be spaced equally
Bohr Models
•1st shell: • Closest to nucleus
• Holds a maximum of 2 electrons
• Must be filled before electrons are placed in 2nd shell
Bohr Models
•2nd shell: • Can hold a maximum of 8 electrons
• Must be filled before electrons are placed in additional shell
Bohr Models
•3rd shell: • Can hold a maximum of 8 electrons
• Must be filled before electrons are placed in additional shell
REACTIVITY• Number of electrons indicates
REACTIVITY
• All atoms WANT to be stable
• Losing, sharing or gaining electrons is a way to become stable
REACTIVITY• WHEN OUTER SHELL IS FILLED,
ELEMENTS ARE STABLE. • “Outer shell” refers to
outermost shell in Bohr diagram that contains electrons.
Periodic Table
• Organizes elements in a particular way and can give a great deal of information about an element
• Understanding the organization and plan of the periodic table can help you obtain basic information about the elements
Dmirtri Mendeleev
• 64 elements arranged by atomic mass, and similar physical and chemical properties
• Predicted properties of missing elements
• Left spaces for “undiscovered elements”
Modern Periodic Table• Revised by Moseley’s work with X-
rays
• 109 elements arranged by atomic number
• Incorporated noble gases and elements that didn’t fit their position in terms of properties
Period
• Horizontal rows • 1-7 • Representing electron shell in
the Bohr model and an energy level in the quantum model
Family
• Vertical columns
• 1-18 left to right OR
• I-VIII followed by A or B
• Elements with similar physical and chemical properties
• Same number of electrons in their outermost shell (valence electrons)
Families Periods• Columns
• Similar properties
• Same number of valence electrons
• Horizontal rows
• Elements not alike
• First element in a period is always active solid and last is always inactive gas
*Note Roman Numeral Number
= Number of Valence Electrons
Number of electrons in last shell of Bohr Diagram
= # of Valence Electrons
Periodic Law
Elements arranged according to atomic number resulting in a reoccurring pattern of similar
properties in different elements.
What is a pure substance?• Substance that contains only 1 kind of
particle. A mixture is defined as a substance that contains 2 or more pure substances.
What is a pure substance?• A material that has consistent properties
and constant composition.
• Examples:
• Water • Tin • Sulfur
• Table salt • Sugar • Baking soda
A MOLECULE IS…• Composed of a cluster of atoms and can be
broken down into those atoms during a chemical change.
A COMPOUND IS…
• A pure substance whose molecules are made of different kinds of atoms. Compounds can be broken down into simpler substances called elements.
METALS
• >75% of the elements • Left & centre of periodic
table (mostly) • Physical properties • Shiny, malleable, ductile, solid at
room temperature (except mercury), conduct heat & electricity
NONMETALS
• 15% of the elements • Far-right side of the
periodic table • Physical properties • No lustre • Brittle • Nonconductors or insulators
of heat and electricity • Solid or gas at room
temperature
METALLOIDS• 6% of the elements • Located on the “staircase” of
the periodic table • Properties of metals AND
nonmetals • Physical Properties:
• Solid at room temperature • Some have lustre • Behave like nonmetals (except
conductivity) • Semiconductors
PROPERTIES OF SUBSTANCES• Stability
• Usefulness
• Durability
• Safety
• Accessibility
• Conductivity
PROPERTIES & POLLUTION• The presence in or introduction
into the environment of a substance or thing that has harmful or poisonous effects.
What are some sources of pollution?
Think about air, soil, land, water pollution
What is mother nature to you?
Why do people need nature?
How can you evolve to benefit mother nature?
Physical Changes• The substance remains the same even though it
may change state or form (shape).
• Can be reversible
• Examples: Cutting, tearing, shattering, mixing, blending, changes in state (melting, freezing, boiling, etc)
Chemical Changes• The original substance is changed into one or
more different substances that have different properties.
• Atoms stay the same but molecules are transformed, so the products are different substances than the reactants.
• Examples: Changes in colour or temperature, production of a gas, rotting, burning, cooking, rusting, forming a precipitate
Physical Properties• Colour • Texture • Odour • Lustre • Clarity
• Taste • Hardness • Malleability • Ductility • Solubility
Chemical Properties• Combustibility
• Flammability
• Reaction with acid
• Types of bonds that it will form
• Chemical stability/reactivity
• Oxidation states
Definitions• Reactants: The “ingredients” of a reaction
• Products: The end results
• Combustion: Substance reacts with oxygen and gives off heat.
• Oxidation: Interaction between oxygen and different substances it may contact.
• Pure substance: A sample of matter with definite and constant composition with distinct chemical properties. Ex. Water, table salt, gold.
Definitions• Mixture: A system made up of 2 or more different substances which
are mixed, but not combined chemically. Ex. Mixing salt with pepper.
• Homogenous mixture: A mixture where the components that make up the mixture are uniformly distributed throughout. Composition is the same throughout. You cannot pick out components of homogenous mixtures. Ex. Air, Vinegar
• Heterogenous mixture: A mixture where the components are not uniform or have regions with different properties. Different samples of mixture are not identical to one another. Ex. cereal in milk, pizza, blood, vegetable soup
Definitions• Precipitate: An insoluble solid that emerges from a liquid solution.
• Heat: The form of energy that flows between 2 samples of matter due to their difference in temperature.
• Ductility: A solid material’s ability to deform under stress. Ex: Ability to be stretched into wire.
• Malleability: The ability of a metal to be hammered into thin sheets. Ex. Gold and silver are highly malleable.
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