Chapter 2 - Basic Chemistry Chapter 2 1 Atoms All matter is...

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Basic Chemistry Chapter 2 1
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Atoms All matter is composed of atoms. Three states of matter Solid defined volume and shape Liquid defined volume, undefined shape Gas undefined volume and shape
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Atoms and Elements Atoms basic unit of all matter Neutrons (no charge) Protons (positive charge) Electrons (negative charge) Atoms are not charged, they are electrically balanced (Equal numbers of protons and electrons) Electrons found in a cloud around the nucleus Protons and neutrons found in the nucleus 3
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Atoms and Elements The Atomic Number (number of protons) determines what type of atom it is Carbon always has 6 protons Oxygen always has 8 protons To Calculate Atomic mass add the number of protons and neutrons together Atomic mass is measured in amu (atomic mass units) 4
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Atoms and Elements Elements consist of only one kind of atom 92 naturally occurring elements Living things contain mainly: CHON All the atoms in an element contain an equal number of protons 5
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Isotopes Isotopes are Atoms of the same element that have different masses They have different numbers of neutrons Carbon atom with 6 neutrons mass = 12 amu (most common isotope) Carbon atom with 7 neutrons mass = 13 amu Carbon atom with 8 neutrons mass = 14 amu 6
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Some isotopes are radioactive Used as molecular labels in science Applications in nuclear medicine Radiation therapy for Cancer treatments radiation damages cancerous cells Radiotracers can be injected into a patient, they can highlight the structure and activity of organs or cells Treatment of thyroid disorders iodine-131 is used to treat an overactive thyroid or thyroid cancer Isotopes
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Electrons Found in different shells surrounding the nucleus Each shell can only hold a limited number of electrons First shell holds 2 Next shell holds 8 Valence electrons are the ones in the outer shell (they will be important in forming chemical bonds) Atoms are stable when their outer shell is full Atoms will reach the most stable combination by losing or gaining electrons in the outer shell 8
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Ions Gaining electrons makes an anion (negative charge) Losing electrons makes a cation (positive charge) Since opposite charges attract each other, anions and cations stick together forming ionic bonds Ionic Bonds occur between metals and nonmetals (NaCl) 9
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Salts The definition of a Salt is a metal bonded to a nonmetal, they always contain ionic bonds When dissolved, the ions dissociate (separate) and are called electrolytes and conduct electricity (important for nerve and muscle function) 10
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Covalent Bonds Sharing valence electrons Atoms can bond to fill their outer electron shells Two or more atoms bonded make a molecule Compounds contain 2 or more different elements 11 Resulting molecules Reacting atoms
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Carbon Makes up to 4 bonds Critical element for biology
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  • Fall '15
  • BarbaraEngebretson
  • DNA, Atom, Chemical bond

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