BASIC CHEMISTRY

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BASIC CHEMISTRY
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Why study Chemistry in Biology?

• Biology - study of LIFE!
• Chemistry - part of chemistry deals with chemical
  compounds. And chemical compounds are important
  to living things.
• Ex glucose- C6H12O6
• water - H2O
  salt - NaCl
  

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Composition of Matter

• Matter - Everything in universe is composed of
  matter
• Matter is anything that occupies space or has
  mass
• Mass quantity of matter an object has
• Weight pull of gravity on an object

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Elements

• Pure substances that cannot be broken down
  chemically into simpler kinds of matter
• More than 100 elements (92 naturally occurring)

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• Each element unique
• chemical symbol
• Consists of 1-2 letters
• First letter is
• always capitalized

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• 99 of the mass of an organism is composed of 6
  elements (SPONCH)
• sulfur (S),
• phosphorus (P),
• oxygen (O),
• nitrogen (N),
• carbon (C),
• hydrogen (H)
• Remaining 1 is composed of trace elements
  required by an organism in minute amounts.
• Iron (Fe)
• Iodine (I)
• Copper (Cu)
• Zinc (Zn)

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Atoms

• The simplest particle of an element that retains
  all the properties of that element
• Our understanding of the structure of atoms based
  on scientific models, not observation

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The Protons

• Contain a positive charge
• Located in the nucleus of an atom
• of protons known as the atomic .
• Number of protons balanced by an equal number of
  negatively charged electrons

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The Neutrons

• Are neutral
• Located in the nucleus of an atom

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The Electrons

• Negatively charged high energy particles with
  little or no mass
• Travel at very high speeds at various distances
  (energy levels) from the nucleus
• Determine the reactivity
• of an element.

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The Nucleus

• Central core
• Consists of positive charged protons and neutral
  neutrons
• Positively charged
• Contains most of the mass of the atom

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Atomic Number

• ALWAYS equal to the of protons.
• Most of the time is the of e- (unless it has
  become an ion)
• Is ALWAYS constant!!! This identifies the
  element.

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Atomic Mass

• The atomic mass of an atom is found by adding the
  number of protons neutrons in an atom (pn)
• Ex

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Isotopes

• Sometimes the number of NEUTRONS can vary among
  atoms when they are in the form of an isotope.

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Isotope Example Carbon
Important in Biology radioactive tracers for
kidney function
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Practice

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• Na Atomic _____
• 23 p ___ e- ___
• Atomic mass _____

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Element Identification

• Au Mercury Pb Mn
• Ar Neon Si Ag
• Al Lithium Mg Bromine
• Be Boron Cl He
• F Sodium K Ni

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Compounds

• Most elements do not exist by themselves
• Readily combine with other elements in a fixed
  ratio

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• A compound is a substance made up of atoms of two
  or more elements
• The proportion of atoms are always fixed
• Chemical formula shows the kind and proportion of
  atoms of each element that occurs in a particular
  compound

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Chemical Formulas - Review

• Subscript after a symbol tell the number of atoms
  of each element
• H20 has 2 atoms of hydrogen 1 atom of oxygen
• Coefficients before a formula tell the number of
  molecules
• 3O2 represents 3 molecules of oxygen or (3x2) or
  6 atoms of oxygen

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Chemical Bonds

• Atoms in compounds are held together by chemical
  bonds. The tendency of elements to combine and
  form compounds depends on the number and
  arrangement of electrons in their outermost
  energy level - called valence electrons

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• The chemical bonds that are important to Biology
  are covalent, ionic, and hydrogen bonds.

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Covalent Bonds

• Formed by the sharing one or more pairs of
  valence electrons of two atoms.
• Strongest type of bond
• Impt to living things
• Found in Biomolecules
• Resulting substance is stable, and is referred to
  as a molecule.

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Ionic Bonds

• Formed between two atoms when one atom loses an
  electron, and the other atom gains an electron.
• This giving receiving results in charged
  particles known as ions - they have an uneven
  of protons and electrons.

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Positive Ions - Cations t

• Atoms that lose electrons are called cations and
  are

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Negative Ions - Anions

• Atoms that gain electrons are called anions and
  are -

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Hydrogen Bonds

• Occurs when H (which is already bonded to an
  electronegative atom) is ATTRACTED to another
  electronegative atom.
• Very weak bond
• Occurs between molecules, not elements.
• Important in DNA.
• Weak attraction - does NOT involve sharing or
  transferring of electrons.

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DNA
Water