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Bell Work

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Title: Bell Work


1
Bell Work
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  • Ionic and Covalent Compounds
  • Ions and molecules can combine to form compounds.
    Because there are millions of compounds,
    scientists organize them into groups. One way
    compounds are grouped is by the kind of chemical
    bond they have. A chemical bond is the combining
    of atoms to form molecules or compounds.

3
  • Ionic and Covalent Compounds
  • Bonding can occur between the valence electrons
    of different atoms. The behavior of valence
    electrons determines if an ionic compound or a
    covalent compound is formed.

4
  • Ionic Compounds and Their Properties
  • The properties of ionic compounds are a result of
    strong attractive forces called ionic bonds. An
    ionic bond is an attraction between oppositely
    charged ions. The compounds that contain ionic
    bonds are called ionic compounds.

5
  • Ionic Compounds and Their Properties
  • Ionic compounds can be formed by the reaction of
    a metal with a nonmetal. Metal atoms become
    positively charged ions and the nonmetal atoms
    become negatively charged ion when the electron
    is transferred. Sodium chloride, table salt, is
    an ionic compound.

6
  • Ionic Compounds Properties
  • Brittleness - Ionic compounds tend to be brittle
    solids at room temperature, so they usually break
    apart when hit. High Melting Points - Strong
    ionic bonds have high melting points. This is why
    most ionic compounds are solids at room
    temperature. Solubility and Electrical
    Conductivity - Many ionic compounds are highly
    soluble and dissolve easily in water. The
    solution that forms when an ionic compound
    dissolves in water can conduct an electric
    current because the ions are charged and are able
    to move freely past each other.

7
  • Covalent Compounds and Their Properties
  • Most compounds are covalent compounds. Covalent
    compounds are compounds that form when a group of
    atoms shares electrons. The group of atoms that
    make up a covalent compound is called a molecule.

8
  • Covalent Compounds Properties
  • Low Solubility Most covalent compounds are not
    soluble in water. Low Melting Points The forces
    of attraction between molecules of covalent
    compounds are much weaker than the bonds holding
    ionic solids together, so less heat is needed to
    separate the molecules of covalent compounds.
    Low Electrical Conductivity Although most
    covalent compounds do not dissolve in water, some
    do. Most of the covalent compounds that dissolve
    in water form solutions that have uncharged
    molecules. Some covalent compounds do form ions
    when they dissolve in water. Many acids, for
    example, form ions in water and these solutions
    do conduct electricity.

9
  • Organic compounds are covalent compounds composed
    of carbon-based molecules. More than 90 of all
    compounds belong to this group.

10
  • All organic compounds contain carbon. Each carbon
    atom has four valence electrons so each carbon
    atom can make four bonds with four other atoms.

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  • Organic compounds may also contain hydrogen,
    oxygen, sulfur, nitrogen, and phosphorus.

12
  • Carbon atoms bond together to form a structure
    called a backbone. It makes the molecule very
    strong. There are three types of structures for
    organic compounds.

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  • Many organic compounds contain several kinds of
    atoms, but some contain only two. Organic
    compounds that contain only carbon and hydrogen
    are called hydrocarbons.

15
  • Organic compounds made by living things are
    called biochemicals. Biochemicals are divided
    into four categories carbohydrates, lipids,
    proteins, and nucleic acids.

16
  • Carbohydrates are biochemicals composed of one or
    more simple sugar molecules bonded together.
    Carbohydrates are used as a source of energy.

17
  • Lipids are biochemicals that do not dissolve in
    water. Fats, oils, and waxes are kinds of lipids.
    Lipids are also used to store some vitamins.

18
  • Lipids store excess energy in the body. When an
    organism has used up most of its carbohydrates,
    it can obtain energy by breaking down lipids.

19
  • Proteins are biochemicals composed of building
    blocks called amino acids. Amino acids are
    small molecules made up of carbon, hydrogen,
    oxygen, and nitrogen atoms, and sometimes sulfur
    atoms.

20
  • Most of the biochemicals found in living things
    are proteins. Proteins function in the body to
    regulate chemical activities, transport and store
    materials, build and repair body structures, and
    regulate processes.

21
  • Nucleic Acids
  • The largest molecules made by living organisms
    are nucleic acids. Nucleic acids are
    bio-chemicals made up of nucleotides.
    Nucleotides are molecules made of carbon,
    hydrogen, oxygen, nitrogen, and phosphorus atoms.

22
  • There are only five kinds of nucleotides, but
    nucleic acids may have millions of nucleotides
    bonded together.

23
  • Nucleic acids have several functions. One
    function is to store genetic information. They
    also help build proteins and other nucleic acids.

24
  • Nucleic acids are sometimes called the blueprints
    of life, because they contain all the information
    needed for a cell to make all its proteins.

25
  • DNA and RNA There are two kinds of nucleic
    acids DNA and RNA.
  • DNA (deoxyribonucleic acid) is the genetic
    material of the cell. DNA molecules can store a
    huge amount of information -- DNA molecules in a
    single human cell have a length of about 2 m.
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