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Unit 2 Atomic Structure and Matter

Unit 2 Atomic Structure and Matter. Matter and Atoms. Matter describes anything that has mass and volume Can matter be invisible? YES Ex. Air. History of atoms. Democritus Was a Greek philosopher in 400 BC Thought the universe was made of atoms and empty space

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Unit 2 Atomic Structure and Matter

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  1. Unit 2 Atomic Structure and Matter

  2. Matter and Atoms • Matter describes anything that has mass and volume • Can matter be invisible? YES • Ex. Air

  3. History of atoms • Democritus • Was a Greek philosopher in 400 BC • Thought the universe was made of atoms and empty space • ATOM comes from the Greek word atomos, which means cannot be divided

  4. Antoine Lavoisier • Was a French chemist in the late 1700’s • Lavoisierproved that matter cannot be created or destroyedduring chemical changes like burningor rusting • The principle is called The Law of Conservation of Matter

  5. Joseph Proust • Was a French chemist • He stated that the basic building blocks of a substanceare always in the same way • For example every molecule of water is made of 2 hydrogen atoms and 1oxygen atom (H2O)

  6. Models of the Atom • What is a model? • A model is anything that lets you create an image in your mind of something that is too big, too small or too complex to understand otherwise • Models can also be used to study events that happen too fast or too slow or would be too dangerous to study otherwise

  7. John Dalton’s Atomic Model • Dalton was an English chemist • In 1803, he proposed that atoms of the same element are the same and atoms of different elements are different • For example, a piece of lead is made up of only lead atoms • He also stated that atomsare the smallest particle of matter.

  8. Atomic Models • Atoms are too small to see with the human eye • We need models to help us understand what they look like • Models are not completely accurate. They represent something that is not easily seen or understood

  9. Atomic Structure • The Nucleus • Is the center of the atom • 99.9% of an atom’s mass is in the nucleus • The nucleus is made of protons and neutrons • Protons have a positive charge • Neutrons have no charge • What charge does the nucleus have? • Positive

  10. The Electron Cloud • Around the nucleus the electrons fly around in random patterns • An electron has an negative charge • An atom has equal numbers of protons and electrons

  11. Electron Cloud • An electron is about 1800 times lighter than a proton or a neutron • Electrons can easily be lost because they are far away from the nucleus. • Have you ever rubbed a balloon on your head? Have you ever zapped your little brother?

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