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Grade 9 Science Unit 1: Atoms, Elements, and Compounds Grade 9 Science... Unit 1 Chapter 1: Atomic theory explains the composition and behaviour of matter. 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. Laboratory Safety Complete activity 1-1A pg. 9 Safety Rules for the Science Lab pages 10-11 General Glassware Chemicals Hot plates and open flames Electrical equipment WHMIS... Page 12 W H M I S workplace hazardous materials information system Hazard Symbols... Page 13 Dangerous Dangerous Container Contents 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. 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. Describing Matter 1. Physical Properties pg. 18 Can be Characteristics of matter that are often observed or measured. either qualitative (observed) or quantitative (measured). •Color •Malleability •Lustre •Conductivity •Boiling point •Melting point •Texture •Magnetism •Density 2. Chemical Properties pg. 19 Observed when substances react with each other. Determines a substances usefulness. •Reactivity •Combustibility Core Lab Activity 1-2C pg. 20 Physical and Chemical Properties 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 Atomic Theory Atomic Theory The descriptions of matter and how it behaves. Has undergone many modifications as new facts became available. An atom consists of a nucleus (of protons and neutrons) electrons in space about the nucleus The Atom Inside the Atom Subatomic Particle Proton (p+) Neutron (n) Electron(e-) Charge Mass Location + Large Nucleus neutral Large Nucleus - Very Energy small levels Early ideas... 2000 years ago Empedocles: matter was composed of four “elements”; earth, air, wind, and fire. 460 BC Democritus: eventually a substance will be cut into a piece that can no longer be cut. He called this piece atomos. Aristotle All matter was composed of four elements Earth, air, water and fire 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. Dalton’s Model... Billiard Ball Model 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. Thomson’s Model... Raisin Bun Model 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). Rutherford’s Model... Planetary Model • Rutherford was able to develop Thomson’s 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. Rutherford’s Experiment • they fired Helium nuclei at a piece of gold foil which was only a few atoms thick. They found that while most of Gold foil the helium nuclei passed through the foil, a small number were deflected and, to their surprise, some helium nuclei bounced straight back. Helium nuclei Rutherford’s 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. Niels Bohr - 1913 He proposed that electrons surround the nucleus in specific energy levels or shells. Each electron has a particular amount of energy. Bohr’s Model... Orbital Model Summary...