1 SCIENCE 9 UNIT B SECTION 2 - · PDF file• identify the number of protons and electrons in each atom, ... • describe the relationship between the structure of atoms in each group

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SCIENCE 9 UNIT B SECTION 2.0 Key Concepts

• Substances and their properties (2.1, 2.2)

• Elements, compounds, and atomic theory (2.1, 2.2)

• Periodic table (2.2, 2.3)

Learning Outcomes

• Distinguish between observation and theory, and provide examples of how models and theoretical ideas are used in explaining observations

• Demonstrate understanding of the origins of the periodic table, and relate patterns in the physical and chemical properties of elements to their positions in the periodic table

• Use the periodic table to: • identify the number of protons and electrons in each atom, as well as

other information about each atom • describe the relationship between the structure of atoms in each group

and the properties of elements in that group

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Unit A - Section 2.0

AN UNDERSTANDING OF THE NATURE OF MATTER HAS DEVELOPED THROUGH OBSERVATIONS OVER TIME.

Section 2.0 2


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2.1 EVOLVING THEORIES OF MATTER

A history over time…

3 Unit A - Section 2.0

8000 B.C.

“Stone Age”

Matter was made up of solid material, which could be fashioned into tools. (Metals were not discovered yet.)

• Stone implements

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6000-1000 B.C.

• Chemists investigated the properties of

only those materials that were of high

value to humans at the time.

• Example: gold and copper

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WHY MIGHT GOLD AND COPPER HAVE BEEN VALUED?

GOLD

• attractive colour and lustre

• did not tarnish (dull the lustre of a metallic surface or discolor)

COPPER

• made pots, coins, tools, jewellery

• naturally brittle (breaks easy), but when heated it is strong

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4500 B.C.

• “Bronze Age”

• The effect of heat on copper, led to the creation of a strong material (bronze) for use as tools.

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1200 B.C.

• “Iron Age”

• Iron combined with carbon to make steel, for even stronger tools.

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EXAMPLE: HITTITES

• People who extracted the iron from rocks.

• Steel made stronger armour and sharper blades.

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NOW LET’S LOOK AT PHILOSOPHERS

• People who first thought about the world and humans’ place in it.

• Their explanations and theories were based on their ideas, not on experimental evidence.

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http://www.artchive.com/artchive/r/rubens/rubens_four_philosophers.jpg

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DEMOCRITUS

• Greek Philosopher

• 460-370 BC

• Used the word “Atomos” [indivisible] to describe the smallest particles that could not be broken down any more.

• Science in Action, pg. 116

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ARISTOTLE

• Aristotle was an ancient Greek philosopher, a student of Plato and teacher of Alexander the Great. He wrote on diverse subjects, including physics, poetry, zoology, logic, rhetoric, politics, government, ethics, and biology.

• Aristotle, along with Plato and Socrates, are generally considered some of the most influential of ancient Greek philosophers.

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ARISTOTLE (CONTINUED)

• He performed original research in the natural sciences, including: botany, zoology, physics, astronomy, chemistry, and meteorology, geometry and several other sciences.

• Aristotle's writings on science are largely qualitative, not quantitative.

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~350 B.C.

• Aristotle’s view: Everything was made out of:

Air, Water, Earth, Fire

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PEOPLE ALSO LOOKED AT JUICES & OILS AS TOOLS

• The word Chemistry came from the word “khemia”, which was Greek for juice of a plant.

• Juices from the juniper tree were used to mummify bodies.

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…AND THEN CAME ALCHEMY

• Alchemy refers to:

• an early form of the investigation of nature

• an early philosophical and spiritual discipline, both combining elements of chemistry, metallurgy, physics, medicine, astrology, semiotics (study of symptoms of diseases), mysticism (belief in personal communication with the divine), spiritualism, and art.

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ALCHEMISTS

• They were not real scientists, but did perform some of the first chemistry experiments; so, they made very valuable contributions to science as we know it today.

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FROM THE 1500’S ON, THE THEORY OF MATTER WAS BASED MORE ON

EXPERIMENTATION.


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1660 • Robert Boyle experimented

with the behaviour of gases.

• He found that particles can be compressed.

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1770

• System for the naming of chemicals was developed.

• Antoine Lavoisier described molecules. He is often referred to as “The Father of Modern Chemistry.”

• He defined some of the substances discovered at that time, including: hydrogen, oxygen, and carbon.

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1780

• It was determined that air was necessary for combustion to occur.

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ATOMIC THEORY OF MATTER

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1808

• Observations of principles were noted during experimentation.

• John Dalton suggested that matter was made up of elements.

• He was the first to define an element as a pure substance that contained no other substances.

• Ex: Gold, Oxygen, Chlorine

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DALTON PUT FORTH THE FIRST MODERN THEORY OF ATOMIC STRUCTURE.

• Each element is composed of a particle called an atom.

• All atoms are identical in mass, but no two elements have the same mass.

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*ATOM*

• The smallest part of an element that is representative of that element.

• Is comprised of protons, neutrons, and electrons.

• A neutral particle made up of a nucleus containing protons and neutrons.

• The number of electrons = the number of protons

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THOMSON

• The first person to discover a subatomic particle (particle smaller than an atom)

• He named them electrons.

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*ELECTRONS*

• Invisible negatively charged particle that orbits the nucleus of an atom

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1897

• Thomson proposed the ‘raisin bun’ model with charged particles.

• He suggested the atom was a positively charged sphere in which negatively charged electrons were embedded.

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1904

• Japanese physicist Hantaro Nagaoka proposed a mini solar system model where negatively charged particles orbited around the nucleus.

• At the centre was a large positive charge, and the electrons orbited around this charge like planets orbiting around the Sun.

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CANADIAN CONTRIBUTIONS

• Ernest Rutherford suggested that atoms were mainly empty space through which positive particles could pass

• At the core, was a tiny positively charged center which he called the nucleus.

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*NUCLEUS*

• Positively charged centre of an atom

• Contains protons and neutrons

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RUTHERFORD ALSO…

• Calculated that the nucleus was only about 1/10 000th the size of the atom - like a green pea in a football field.

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1922

• Electrons are believed to rotate randomly around the nucleus.

• Danish Researcher, Niels Bohr, suggests that electrons move in specific circular orbits or electron shells.

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*ELECTRON SHELL*

• Orbit of electrons around the nucleus of the atom

• Bohr also proposed that electrons jump between these shells by gaining or losing energy.

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1932

• British Physicist James Chadwick discovered that the nucleus contained positively charged particles called protons and neutral particles called neutrons.

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NUCLEUS OF AN ATOM CONTAINS:

*Protons*

Positively charged

particle in the

nucleus of an atom.

*Neutrons*

Neutral particle in

the nucleus of an

atom.

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TODAY

• The 'quantum model' describes the atom as a cloud of electrons around a nucleus.

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SUMMARY

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ELEMENTS, COMPOUNDS, AND ATOMS (9:29)


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HOMEWORK!

• Check and Reflect • Page 121

• # 1 – 8 • (Yellow Book – pg. 30)


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TOPIC 2.2 AN UNDERSTANDING OF THE NATURE OF

MATTER HAS DEVELOPED THROUGH OBSERVATIONS OVER TIME


LOOKING FOR PATTERNS

• Early chemists used symbols of the sun and the planets to identify the metallic elements known to them.

• This later became a problem, when more elements were discovered, because they ran out of planets.

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SYMBOLS FOR EARTH, AIR, FIRE, AND WATER

• Some of the earliest symbols were those used by the ancient Greeks to represent the four elements.

• These were adopted by Plato, using the Pythagorean geometric solids:

Earth Air Fire Water

cubic octahedral tetrahedral icosahedral atoms atoms atoms

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JOHN DALTON’S SYMBOLS

• John Dalton developed a new set of symbols in the early 1800's to improve communication between chemists.

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JÖNS BERZELIUS • Berzelius later revised

Dalton's symbols by replacing them with letters instead of pictures.

• He represented the elements by their first letter (capitalized), or their first two letters (first one capitalized and the second letter was lower case).

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http://scienceworld.wolfram.com/biography/photo-credits.html#Berzelius

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AN ORDER FOR THE ELEMENTS

• Elements were listed in order of their

atomic mass.

*Atomic mass* • the mass of one atom of an element. • It is represented in atomic mass units

(amu).

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LAW OF OCTAVES

• English chemist John Newland's "law of octaves" identified the pattern in which the properties of the elements seemed to occur.

• Having arranged the 62 known elements in order of increasing atomic masses, he noted that after intervals of eight elements similar physical/chemical properties reappeared, which is similar to the octave scale in music.

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1869

• Russian Chemist, Dmitri Mendeleev later revised the pattern in 1869.

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FINDING A PATTERN

•Mendeleev collected the 63 elements known at the time and arranged them according to their properties (which he wrote on a file card). He arranged the cards into a 'solitaire-like' table.

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MIND THE GAP

• By sorting and arranging the elements in this way, Mendeleev was able to identify gaps where elements, not yet discovered, would be able to fit.

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HOMEWORK!

• Check and Reflect • Page 125

• # 1-3, 7 • (Yellow Book – pg. 33)


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2.3 THE PERIODIC TABLE TODAY


THE PERIODIC TABLE TODAY

•About 112 elements are known today.

• They are organized into what is called 'The Periodic Table of Elements‘

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METAL THAT MELTS IN YOUR HAND.

• In 1875, Gallium was discovered and proved that Mendeleev's organization of the elements worked, because it fit in where he had placed a (?).

• Some uses: • to create mirrors

• in solar panels

• as agents in nuclear medicine imaging

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THE LEGACY OF PIERRE AND MARIE CURIE (8:29)


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Ms. El Cid visiting the burial site of Pierre

and Marie Curie at the Pantheon in Paris,

France (2012)

THE NEXT (?) WAS NOT REPLACED UNTIL 1939 WHEN FRANCIUM WAS

DISCOVERED.

• This element was named for France.

• It is the heaviest alkali metal.

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http://en.wikipedia.org/wiki/France

http://en.wikipedia.org/wiki/Alkali_metal

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MEET THE ELEMENTS

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Horizontal rows are called periods. (Numbered 1-7)

Vertical columns form a group, or

family of elements, which have similar

chemical properties.

(Numbered 1-18)

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*ATOMIC NUMBER*

• Found in the top left hand corner of the table

• It shows the number of protons & electrons in one atom of the element.

Atomic number = # of protons = #of electrons

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*MASS NUMBER*

• the sum of the protons and neutrons in the nucleus of 1 atom of the element

Mass number = # of protons + #of neutrons

• like atomic mass but is a little different

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RECALL: ATOMIC MASS • The average mass of an element in atomic

mass units (amu.)

• The atomic mass is a decimal number on the Periodic Table because it's an average of the various isotopes (one or more atoms that have the same atomic number but different mass numbers) of an element.

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*ATOMIC SYMBOL*

• These are almost always the one or two letters that represent an element.

• They're used worldwide and usually relate to the name of the element or the Latin name of the element. An example of this is "O" for Oxygen and “K" for potassium from the latin name “kalium”.

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HOMEWORK!

• Science 9 (Yellow) Reference Book • Page 37: Atomic

Number and Mass Number Chart


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*ION CHARGE*

• An ion is an atom or group of atoms that have lost or gained one or more electrons.

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PATTERNS OF INFORMATION

• Metals: • shiny, malleable and ductile • conduct electricity • solid, except Mercury

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• Non-metals: • solids or gases at room temperature with

the exception of Bromine which is a liquid • solids are dull and brittle • do not conduct heat or electricity very well

except carbon • in groups 14 to 16 in the periodic table. • can not be made into wire or sheets

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• Metalloids: • have both metal and non-metal properties • Some of them are semi-conductors, which

means, they can carry an electrical charge under special conditions.

• great for computers and calculators.

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MORE PATTERNS…

• Transition Metals - the 38 elements in groups 3 to 12 are called transition metals. The only elements in this group known to produce a magnetic field are iron, cobalt and nickel.

• Other Metals - there are 7 elements considered "other metals" in groups 13 to 15. All these elements are solid with a high density. Examples are tin, aluminum and lead.

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MORE PATTERNS…

• Rare Earth Elements - there are 30 rare earth elements. Many of them are synthetic or man-made. They're found around group three of the periodic table and the sixth and seventh groups. Possible uses include cathode-ray tubes & fibre optics. We import a lot from China.

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CHEMICAL FAMILIES

• a term used to describe a group of related elements that have similar properties.

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ALKALI METALS (GROUP 1)

• Do not occur freely in nature and are softer than most metals

• Does not include Hydrogen

• Like all metals, they are great heat conductors and can even explode if exposed to water or air – they are very reactive and need special storage.

• They easily give off an unpaired electron by forming a compound.

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ALKALINE-EARTH METALS

(GROUP 2)

• Because they are extremely reactive, they are not found freely in nature.

• all react with water in the same manner

• not as reactive as the alkali metals

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HALOGENS (GROUP 17)

• All 5 halogens are non-metallic elements. • They are the most reactive non-metals. • Compounds that contain halogens are

called ‘salts’. • At room temperature, they are in three

states of matter: solid, liquid and gas.

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NOBLE GASES (GROUP 18)

• Do not react with other elements

• the MOST STABLE elements (because all of them have the maximum number of electrons possible in their outer shell)

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ATOMIC RADII (ATOM SIZES)


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SUMMARY

• ATOMIC NUMBER - The number above the element’s symbol on the left is the atomic number.

• ELEMENT NAME - See name on the periodic table.

• ELEMENT SYMBOL - See letter symbols on the periodic table.

• ATOMIC MASS - The number below the element’s name is the atomic mass (units: amu). • Atomic mass = mass of protons + mass of neutrons

• MASS NUMBER = # of protons + # of neutrons • The atomic mass (aka isotope mass or atomic weight) rounded to

the nearest whole number is the mass number.

• NUMBER OF PROTONS = atomic number

• NUMBER OF NEUTRONS = mass number – atomic number

• NUMBER OF ELECTRONS = # of protons (in a neutral atom)

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HOMEWORK!

• Science 9 (Yellow) Reference Book • Page 40 – Skill

Practice • Page 41 – First 18

Elements Chart • For a list of mass

numbers, see the chart on pg. 49!

• Page 45 – Elements Crossword Puzzle


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Element Mass

number

# of

protons

# of

neutrons

# of

electrons

vanadium 51

nickel 58

phosphorus 31

bromine 79

beryllium 9

argon 40

magnesium 24

uranium 238

silicon 28

chromium 52

titanium 48

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Atomic Number

Element Name

Element Symbol

Atomic

Mass (amu)

Mass number

Number

of Protons

(+ charge)

Number

of Neutrons

Number

of

Electrons (- charge)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

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THE PERIODIC TABLE VIDEO

http://www.learner.org/vod/vod_window.html?pid=799


http://www.learner.org/vod/vod_window.html?pid=799

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HOMEWORK!

• Check and Reflect • Page 134 • # 1-6, 9

• (Yellow Book - pg. 43)

• Assess Your Learning • Page 136 • # 3-6, 8-10

• (Yellow Book – pg. 44)

• Yellow Book • Page 46 - Elemental

Tale


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HOMEWORK!

• Yellow Book • Page 47 – PEN Chart

• Page 48 – Study of Atoms


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HOMEWORK!

• Yellow Book • Page 50-51 – Section 2

Review Worksheet


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Documents

1 SCIENCE 9 UNIT B SECTION 2 - · PDF file• identify the number of protons and electrons in each atom, ... • describe the relationship between the structure of atoms in each group