EEH103 Lecture Notes - Lecture 3: Chemical Bond, Eugenius Warming, Unit
WEEK 3 LECTURE NOTES:
METABOLISM:
oRefers to all the chemical reactions that take place within an organism.
oComplex molecules are broken down to produce energy or take in energy
Example: eating a spoonful of sugar.
Once inside the body, sugar molecules are broken down into simpler molecules with the release
of energy.
That energy is then used by the body for a variety of purposes such as keeping the body warm.
CELLULAR METABOLISM:
oMetabolic substances are transported to individual cells by the bloodstream
oPass through cell membranes and entre the cell interior
oBreaks down the substances even more (to elements)
Example: sugar molecules are broken down inside a cell into carbon dioxide and water
ELEMENTS:
ois a pure substance
oCANNOT BE CREATED OR BROKEN DOWN BY ORDINARY CHEMICAL MEANS
oBODY CANNOT MAKE THESE, THEY COME FROM WHAT YOU EAT AND BREATHE
Examples:
oOXYGEN: 65%
oCARBON: 18%
oHYDROGEN: 10%
oNITROGEN:3%
ELEMENTS AND ATOMS:
oThe smallest, most fundamental material components of the human body are basic
CHEMICAL ELEMENTS
oSMALLEST UNIT of an element is an ATOM
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ATOM STRUCTURE:
oMade up of subatomic particles: PROTON
(POSITIVE), ELECTRON (NEGATIVE), NEUTRON
(NEUTRAL)
oProton and neutron in centre of the atom and
gives mass to atom.
oElectrons spin around the nucleus and equals the number of protons.
oPOSITIVLEY CHARGED ELECTRONS GIVE THE ATOM STABILITY
oIF THE NUMBER OF PROTONS AND ELECTRONS ARE THE SAME=
BALANCED OR STABLE ATOM
CHEMICAL BONDS: BEHAVIOUR OF ELECTRONS-
oElectron shells or VALENCE SHELL hold electrons (outside of nucleus)
oOne to five electron shells present
oFirst shell holds a total of 2 and the rest can
hold a total of 8 (OCTET RULE)
oFor an atom to be considered “stable” the
shells need to be full, if not it needs to bond or
react with another atom to be complete.
oIf the valence is not full then it is considered
reactive
EXAMPLE:
oOxygen has 8 electrons in total, 6 in the outer valence shell
oHydrogen has 1
oOxygen needs two electrons to fill its valence shell
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oIt commonly interacts with two atoms to hydrogen forming H2O
CHEMICAL BONDS:
oAtoms link by forming a chemical bond
o2 or more of the same atom forming is called a molecule (example: 2 oxygen atoms form
together to make oxygen gas)
o2 or more different atoms forming is called a compound (example: 2 hydrogen and 1 carbon
atom form together to form water
oMolecules are the building chemical blocks of all body structures
ATOMS TO MOLECULES:
o3 types of chemical bonds, ionic, covalent and hydrogen
IONIC:
oan atom that has an electrical charge (negative or positive) is an ion
oionic bond is an ongoing close association between ions of OPPORSITE CHARGE
oAtoms either DONATE or RECEIVE electrons
COVALENT BONDS:
oShare electrons by stabilising the relationship
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Document Summary
Metabolism: refers to all the chemical reactions that take place within an organism, complex molecules are broken down to produce energy or take in energy. Once inside the body, sugar molecules are broken down into simpler molecules with the release of energy. That energy is then used by the body for a variety of purposes such as keeping the body warm. Cellular metabolism: metabolic substances are transported to individual cells by the bloodstream, pass through cell membranes and entre the cell interior, breaks down the substances even more (to elements) Example: sugar molecules are broken down inside a cell into carbon dioxide and water. Elements: is a pure substance, cannot be created or broken down by ordinary chemical means, body cannot make these, they come from what you eat and breathe. Examples: oxygen: 65, carbon: 18, hydrogen: 10, nitrogen:3% Elements and atoms: the smallest, most fundamental material components of the human body are basic.
