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Intro to Atoms

Intro to Atoms. Atoms : the basic particle in which all elements are made Nucleus : The central core of an atom containing protons and neutrons In the nucleus are: Proton : small, positively charged particle in the nucleus of an atom ( + symbol)

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Intro to Atoms

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  1. Intro to Atoms Atoms: the basic particle in which all elements are made Nucleus: The central core of an atom containing protons and neutrons In the nucleus are: • Proton: small, positively charged particle in the nucleus of an atom ( + symbol) • Neutron: Neutral charged particle in the nucleus of an atom Outside the Nucleus: • Electron: tiny, negatively charged particle that moves around the nucleus of an atom

  2. Laws of Science Law of Conservation of Matter • Matter cannot be created or destroyed Law of Conservation of Mass Established by French Chemist Antoine Lavoisier • In a chemical reaction, the mass of the products equals the mass of the reactants. THIS IS EXTREMELY IMPORTANT WHEN BALANCING EQUATIONS

  3. What’s the MATTER? Matter: anything that has mass and takes up space. Mass: measurement of how much matter is in an object Element: a substance that cannot be broken down into any other substances by chemical or physical means Compound: a substance of 2 or more elements Mixture: 2 or more substances that are mixed together, but NOT chemically combined

  4. Atomic Models Early Models/Theories of the Atom: Dalton’s Atomic Model: - All matter is composed of atoms- Atoms cannot be made or destroyed- All atoms of the same element are identical- Different elements have different types of atoms - Atoms of 2 or more elements can join together to form a compound

  5. Modern Atomic Model – NOT ON YOUR PAPER! • Electrons form a negatively charged cloud around the nucleus • Cannot determine the location of an electron at any given time

  6. Atomic Models continued… JJ Thomson’s Model: • Atom is positively charged • Discovered Electrons Rutherford’s Model: • Protons and the nucleus • Electrons orbit around the positively charged nucleus Chadwick’s Model: • Discovered neutrons Bohr’s Model: • Electrons move in specific layers (shells) • Electrons move when atoms absorb or give off energy, moving from one shell to another

  7. Atoms and Elements Atomic number • number of protons in an element • Number of electrons the element has Atomic mass: mass of one atom of the element How to calculate neutrons: atomic mass # - atomic number Valence electrons: electrons that can be transferred from one atom to another or may be shared between atoms Chemical symbol: symbol for element (H – Hydrogen) (C – Carbon)

  8. Periodic Table Dmitri Mendeleev • Created first Periodic Table • Arranged elements in order of increasing atomic mass • Placed similar elements in the same group according to their reactions Periods: a horizontal row in the P.T. Groups: vertical columns in the P.T. – also known as families due to similar characteristics

  9. Groupings • Metals (Alkali , Alkali Earth) • Nonmetals • Nobel Gases • Transition Elements • Halogens • Common Elements

  10. Valence Shells Group 1 = 1 valence electron Group 2 = 2 valence electrons Group 13 = 3 valence electrons Group 14 = 4 valence electrons Group 15 = 5 valence electrons Group 16 = 6 valence electrons Group 17 = 7 valence electrons Group 18 = 8 valence electrons (full shell)

  11. Properties of Metals • Classified by its physical properties such as shininess, malleability, ductility, and conductivity. Malleable: can be hammered flat or into other shapes Ductile: can be pulled out into a long wire Conductivity: ability to transfer heat from one object to another

  12. Metals continued… Chemical properties: ability of a pure substance to change into another substance. Reactivity: The speed in which an element combines or reacts with other elements Corrosion: the wearing away of metal due to a chemical reaction Metals can be considered an alloy which is a mixture of a metal with one other element (usually found together in nature)

  13. Physical and Chemical Properties Physical Chemical Def: a change that produces one or more new substances A chemical reaction will take place Burning paper Corrosion Rusting Milk or eggs going BAD • Def: a change that does not result in the formation of any new substances • Examples: Dissolving sugar in water Melting ice cubes Boiling water Crumbling Paper

  14. Nonmetals • Lack the properties of metals • Poor conductors of electricity and heat • Reactive with other elements • Dull and brittle (break easily) • Good insulators

  15. Metalloids & Noble Gases Metalloids Noble Gases Unreactive elements Exist in Earth’s atmosphere • Metalloids has characteristics of both metals and nonmetals • Semiconductors: substances that can conduct electricity under some conditions

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