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Chemistry Unit: The Study of Matter

Chemistry Unit: The Study of Matter. Grade 9 Science. Outline the development of scientific thought as it relates to matter and the atomic structure. Define element and understand its relationship to the concept of matter. Describe the understanding of the structure of the atom. Key Words

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Chemistry Unit: The Study of Matter

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  1. Chemistry Unit:The Study of Matter Grade 9 Science

  2. Outline the development of scientific thought as it relates to matter and the atomic structure. • Define element and understand its relationship to the concept of matter. • Describe the understanding of the structure of the atom. • Key Words • Element atom pure substance • Hypothesis alchemist plum pudding model • Subatomic neutral electron • proton

  3. Developing Models of Matter

  4. Democritus (400 BCE) • Hypothezised matter was tiny particles in constant motion. • Cannot be broken apart –solid. • Eternal (unable to create or destroy) • Surrounded by an empty space. • *called particles atomos– meaning “indivisible” - ATOM

  5. Aristotle(350 BCE)   • Ancient Greek philosopher. • Believed matter was made of four elements. • His theory was accepted by all.

  6. Alchemy and the Middle Ages (500 – 1600 CE) • Concerned with metallurgy (study of properties of metals). • Goals- turn common metals into gold or silver. • - find a substance to give eternal life. • (the key to both is called the Philosopher’s Stone) • Developed observation, experimentation, measurement and • classification – first “scientists.” • Called “alchemists”

  7. Lavoisier (1750) • 13 known substances – gold, copper, arsenic, bismuth, antimony, iron, mercury, carbon, lead, silver, sulphur, tin, zinc. • Performed experiments to show water and air were • mixtures of elements. • Defined the term ELEMENT - a fundamental pure • substance that cannot be broken down into simpler parts. • Discovered23more elements.

  8. Dalton (1800) • FIRST ATOMIC THEORY • all matter is made of indivisible particles - atoms. • Atoms of each element are unique (differ by mass). • Compounds are combinations of different elemental atoms. • Atoms cannot be created or destroyed. • (Law of conservation of matter)

  9. Thomson(1890) • Hypothesized (guessed) first subatomicparticles –electron. • Electrons have a small mass and negative electric charge. • Atom is sphere with equal number of positive charges mixed • with negative electrons - Plum pudding model. • Overallatom is neutral electrically.

  10. Rutherford (1910) • Conducted “Gold Foil Experiment.” • Discovered the atomic nucleus. • Nucleus is a small, dense (heavy), positively charged core. • Positive charges due to another subatomic particle - protons • Hypothesized atom composed of mostly space with a centre • nucleus and small electrons floating around.

  11. Chadwick (1932) • discovered the neutron in the nucleus • Neutrons have no charge and are the size of protons. • THREE subatomic particles: • - dense positive nucleus (protons and neutrons). • - negativeelectrons floated around.

  12. Dalton - each element has its own kind of atom • - compounds are formed when elements link together
 - atoms cannot be created or destroyed • - billiard ball model • Thomson - discovered negatively charged electrons • - hypothesized equal positive and negative particles 
 • - plum pudding model • Rutherford - discovered nucleus (goldfoil) and positive protons • - hypothesized atoms were mostly empty space • - beehive model

  13. The Atom Contains 3 subatomic particles: The dense center (nucleus) of the atom contains: Neutron - a particle with no charge. Proton - a particle with a positive charge. Electrons are tiny particles that move around the nucleus. - negative electrical charge. - same # of positive and negative charges = neutral.

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