Unit 1: Atoms, Elements, and Compounds

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Grade 9 Science

• Unit 1 Atoms, Elements, and Compounds

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Grade 9 Science... Unit 1

• Chapter 1 Atomic theory explains the composition
  and behaviour of matter.

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Lab Safety... A Review

• Safety rules and procedures MUST be your top
  priority.
• Know them before you do the lab and use them
  while doing the lab.

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Complete activity 1-1A pg. 9
Laboratory Safety
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Safety Rules for the Science Labpages 10-11

• General
• Glassware
• Chemicals
• Hot plates and open flames
• Electrical equipment

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WHMIS... Page 12

• W workplace
• H hazardous
• M materials
• I information
• S system

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Hazard Symbols... Page 13

• Dangerous Container

• Dangerous Contents

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Properties of Matter

• Matter is anything that has mass and volume.
• Mass is the amount of matter in a substance or
  object.
• Volume is the amount of space a substance or
  object occupies.

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• Matter is made up of elements.
• Elements are substances that contain one type of
  matter and cannot be broken down or separated
  into simpler substances.

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Describing Matter

• 1. Physical Properties pg. 18

• Can be either qualitative (observed) or
  quantitative (measured).

• Characteristics of matter that are often observed
  or measured.

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• Color
• Malleability
• Lustre
• Conductivity
• Boiling point
• Melting point
• Texture
• Magnetism
• Density

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• 2. Chemical Properties pg. 19

• Observed when substances react with each other.

• Determines a substances usefulness.

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• Reactivity
• Combustibility

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Core Lab Activity 1-2C pg. 20

• Physical and Chemical Properties

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Theory vs. Law

• A law is better supported than a theory.
• Most laws are supported by different and robust
  experimental evidence.
• Theories can change or be modified
• Laws rarely change

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Atomic Theory
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Atomic Theory

• The descriptions of matter and how it behaves.
• Has undergone many modifications as new facts
  became available.

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• An atom consists of a
• nucleus
• (of protons and neutrons)
• electrons in space about the nucleus

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The Atom
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Inside the Atom
Subatomic Particle Charge Mass Location
Proton (p) Large Nucleus
Neutron (n) neutral Large Nucleus
Electron(e-) - Very small Energy levels
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Early ideas... 2000 years ago

• Empedocles matter was composed of four
  elements earth, air, wind, and fire.

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• 460 BC
• Democritus eventually a substance will be cut
  into a piece that can no longer be cut.
• He called this piece atomos.

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Aristotle

• All matter was composed of four elements
• Earth, air, water and fire

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Development of Atomic Theory

• John Dalton - 1808
• He suggested that the particles that make up
  matter are like small, hard spheres that are
  different for different elements.
• He defined an atom as the smallest particle of an
  element.

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Daltons Model... Billiard Ball Model
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• J.J. Thomson - 1898
• He suggested that all atoms must contain
  electrons (negative charge).
• His model pictured a positively charged ball with
  the negatively charged electrons embedded in it.

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Thomsons Model... Raisin Bun Model
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• Ernst Rutherford - 1910
• He discovered that atoms have a nucleus.
• There are two kinds of particles in the nucleus
  protons (positive charge) and neutrons (neutral).

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Rutherfords Model... Planetary Model
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• Rutherford was able to develop Thomsons model
  due to the development of new technologies. (gold
  foil experiment)
• The development of cyclotrons and proton
  accelerators have further developed the model
  accepted today.

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Rutherfords Experiment

• they fired Helium nuclei at a piece of gold foil
  which was only a few atoms thick.

Gold foil
They found that while most of the helium nuclei
passed through the foil, a small number were
deflected and, to their surprise, some helium
nuclei bounced straight back.
Helium nuclei
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• Rutherfords new evidence allowed him to propose
  a more detailed model with a central nucleus.
• He suggested that the positive charge was all in
  a central nucleus. With this holding the
  electrons in place by electrical attraction
• However, this was not the end of the story.

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• Niels Bohr - 1913
• He proposed that electrons surround the nucleus
  in specific energy levels or shells.
• Each electron has a particular amount of energy.

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Bohrs Model... Orbital Model
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Summary...