Chemicals Of Life Flashcards
Srikandi 4flat together
Living organism made from
Organic and inorganic molecule
What is organic molecule
Large, complex molecule with backbone of C atom
What is inorganic molecule
Small, simple molecule that lack of C atom or have only 1
Atom combines by chemical bonding to form
Molecule
4 important bonds
Ionic bonds
Covalent bonds
H bonds
VDW bonds
Ionic bond involves
Transfer of electron
What happen in ionic bond
1 atom lose e form +ve ion
1 atom gain e form -ve ion
Charge different so they attract each other
Covalent bonds involve
Share 1 or more pairs of e
Types of covalent bond
Polar
Non polar
What is non polar c.b
Atoms same proton no. Exert
Same pull and electron, share e equally
Charge in non polar c.b
No diff in charge between two end of atom
What is polar c.b
Atoms of diff elements (diff proton no.) Dont exert same pull on e
Atom that pull more e become slightly -ve
Atom pull less e become slightly +ve
Charge in polar c.b
No net charge
Define electronegativity
Tendency of atom to attract electron towards itself. Depends on atomic no. and dist between valence e and nucleus (bak kata teacher noor, nak jadi negative ion)
Try explain polar c.b in water
O more electro-ve than H. Electron shared are pulled more towards O. O slightly -ve , H slightly +ve
What is H bond
Attraction between more electro-ve atoms (from one polar c.b)and H atom (from another polar c.b)
Can H bond be in same or diff molecule?
Both
What is VDW interactions
A molecule with non polar c.b may have +ve and -ve charged regions. This is bcs e is in constant motion, they are not symmetrically distributed
Its a weak interaction and occur only when atoms and molecules are very close
Importance of water
Surround the cell
70-95% in cell
Reactant of many chemical reaction in life
Structure of water
Have 1 O and 2 H
O > electro-ve than H
So O slightly -ve , H slightly +ve
Form polar molecule
Charge in water
No net charge but charge are unevenly distributed
Why water liquid can flow
The H bond between water molecule constantly form break reform
What makes water stable compound
Has H bond between molecules
Collective H bond produce strong structure allowing water to be stable compound
Due to polarity
Water molecule attracts and form bond (H bond) with each other
5 properties of water
Cohesion adhesion High specific heat cap. High heat Vap Lower density of ice Water as principal solvent
What is adhesion
Attraction between water and polar substance like container
Make things wet
Cohesion
Attraction betwern water molecules that produce surface tension (skin of water)
Allow insects to walk on water (water strider)
Water surface provide breeding and feeding place
Adhesion+cohesion
Capillary action
What is capillary action
Tendency of water to move in narrow tube against the gravity force
How capillary action works in plant
Capillary action in plants allow water to flow upward through the vascular system. As water evaporate from leaves surface, water molecules that are cohered to that evaporating molecules move upward. The water stays in tubular shape bcs it i adhered to the lining of plant vascular tube
Define specific heat cap
Amount of heat absorbed or lost by 1g substances to change it temp by 1°C
What is specific heat cap of water
4.2 J (large amount)
Why water has high specific heat cap
Bcs heat is needed to break the H bomds between water molecule therefore change in temp only cause slight change in water temp
Significance of high spec heat cap
Temp change is minimized. Water helps to moderate temp of organism and environment