Physico chemical basis of lifePresentation Transcript
Physico-Chemical Basis of Life Joy Grace Tablante More Free PowerPoint Templates at SmileTemplates.com
Matter makes up both living and nonliving things.
Biologists study the nonliving particles
(chemical aspect) of which matter is made of in order to understand better the biological function of living things.
Living things also depend on a constant supply of energy.
Together matter and energy are the physical basis of Life.
Matter Flowchart MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous Mixture Compound yes no Element MIXTURE PURE SUBSTANCE Can it be chemically decomposed? no yes Is the composition uniform? no yes Colloids Suspensions
Chemicals play many more roles in life
Making up our bodies, those of other organisms, and the physical environment
The food we eat
The water we drink
Water makes up 65 to 90% of the weight of the human body
Biological functions starts at the chemical level
Life is composed of matter
Matter is composed of chemical elements
Each element consists of one type of atom
Certain atoms combine to form the complex molecule chlorophyll
Many chlorophyll molecules are located in organelles called chloroplasts
Many chloroplasts are located in cells of photosynthetic tissues in structures ( organs ) such as leaves of plants
Matter—anything having mass and occupying space
Mass—a measure of the amount of matter that an object contains
Mass vs Weight
Weight is the measure of how strongly an object is pulled by earth’s gravity and consequently varies as a function of distance from the earth’s center. Mass does not vary with its position
Substances can either be classified as elements or compounds
Elements: pure, cannot be broken down
Compounds: Can be broken down into two or more substances
NOTE: for further information about compounds please view
Bio-Substances ppt at www.biolojoy.blogspot.com
Compounds can either be Inorganic or Organic. These compounds are nutrients which provide energy or materials for all cell activities. Living things are mostly made of organic compounds that contain carbon and hydrogen. Often they contain oxygen too
These organic compounds can also have amounts of nitrogen, calcium and phosphorous. They may have varying small amounts of other elements called “trace elements” like potassium, iodine, sulfur, iron, magnesium and sodium.
Living things also need inorganic compounds like water and salts.
Are particular kind of matter that cannot be separated into other kinds and are listed in the chart known as the periodic table
Scientists have found that 92 different kinds of elements exists in nature. They have also created additional ones in the lab.
Just as primary colors combine in different ways to make up every color we can see, the different elements combine in different ways to make up all substances.
Metals such as gold, silver and iron –in their pure forms are all elements.
Living organisms are composed of about 25 chemical elements
There are 11 major elements in the human body.
4 of these elements make up 96% of the bulk material in the human body
The remaining elements constitute 4% of the material of the human body.
Are essential to life, but occur in minute amounts
Dietary deficiencies in trace elements
Can cause various physiological conditions
Calcium: Deficiencies can contribute to osteoporosis.
Copper: Deficiencies of copper can cause premature hair graying, sterility and premature wrinkling of the skin.
Iodine: Deficiencies of iodine can cause a thyroid imbalance or reduced fertility.
Selenium: Deficiencies of selenium can cause people to age prematurely or to have slower than normal recovery from illnesses.
Zinc: Deficiencies of zinc can cause sterility, impotence and even depression.
Iron: is a component of molecules that transport oxygen in blood.
A diamond is made of element carbon.
All elements are made of tiny particles called atoms.
Balloons that rise are filled with the element helium.
The mercury in a thermometer is a liquid element.
Each of the 116 elements consist of only one type of atom.
from the Greek word “ atomos” for indivisible (cannot be divided)
If you keep slicing an element in half, eventually you slice to its smallest particle, an atom
3,000,000 C atoms stretch across the diameter of a period!
Pinheads have a diameter of about 0.001meters (a millimeter ).
An atom has a diameter of 0.00000000025 meters.
(1 atom/2.5 x 10-10 meters) * (1 x 10-3 meters) = 4 x 106 atoms
Four million of them could line up across the head of a pin.
The nucleus is about 0.01% the diameter of the atom as a whole . If the nucleus had a diameter equal to that of a pinhead, then the atom itself would have a diameter of some 10 meters ( about 39 and a half feet ).
In other words, atoms are mostly empty space!
Protons (p + )
Packed in nucleus
The number of protons determines the elements chemical identity
Have a + positive charge
The # of protons is called the ATOMIC NUMBER
Neutrons (n 0 )
Same size as protons
1 atomic mass unit (amu)
Also packed in nucleus
No charge, neutral
The number of protons plus the number of neutrons is called the MASS NUMBER
Electrons (e - )
Have a -negative charge (equal and opposite to the positive charge of a proton)
Whirl around the nucleus in area call energy levels or orbitals
Their exact path is completely unpredictable
1 st energy level holds 2 e - , 2 nd energy level holds 8 e -
Like a fly buzzing around Force Field
Is adding the number of protons to the number of neutrons
Subtracting the atomic number from the mass number gives you….. the number of neutrons
By definition, atoms are neutral , they have no charge.
In other words, the number of protons equals the number of electrons.
Example: A Lithium has 3 protons and 3 neutrons inside the nucleus with 3 electrons orbiting around the nucleus as shown below.
IONS “ charged” atoms
Atoms that are not neutral
They have unequal numbers of electrons and protons
Some might have more protons than electrons (Ca +2 , H + ) cation
Others might have more electrons than protons (Cl - , O -2 ) anion
CATION ANION when Li, Be and Ca loose their electrons the "new" valence electrons in the ion are drawn in. These elemental ions are stable in the sense that they will not readily gain or loose electrons. However, since they are charged they can combine electrostatically to form ionic bonds. the resulting compound is called "ionic" or "salt", e.g., Ca+ + 2Cl- ---> Ca(Cl)2 = calcium chloride. H + : a positively charged hydrogen ion H : the hydrogen atom H - : a negatively charged hydrogen ion
Same element with same number of protons, but a different number of neutrons.
Alternative form of the same element
The mass number is different, but the atomic number is the same
Some isotopes are radioactive
Radioactive Isotopes (radioisotopes)
Some isotopes are radioactive
Radioactive elements have nuclei that are unstable, they “decay”
The nucleus falls apart
The nucleus emits high-energy particles that are like tiny bullets.
Usually caused when the number of neutrons is much greater than the number of protons
The emitted particles/energy can damage cells via mutation ( if powerful enough )
Some are weakly radioactive
Some can be used as “tracers”
To follow molecules as they undergo chemical changes in an organism
Some can be used to target and kill specific cells (radioactive iodine treats hyperthyroidism)
Radioactive tracers are often used for diagnosis
- In combination with sophisticated imaging instruments
How brain function is studied now? PET, CAT, MRI, etc. Music Appreciation Hearing, speaking, seeing, thinking about words
How an atom hooks up with other atoms to form molecules/compounds
An atom’s reactivity depends on how many electrons are in its highest Energy level
A happy, stable atom has a full outermost Energy level
8 is best
Depends on electrons
Atoms will either gain, lose, or share electrons to have a full outer level of electrons
Reactive elements have partly-filled outer energy levels
Inert (nonreactive) elements have a filled outer energy levels
Family 18, the noble gases
Atoms whose shells are not full, tend to interact with other atoms and gain, lose , or share electrons. These interactions form chemical bonds
Types of chemical bonds:
Are attraction between ions of opposite charge
When atoms gain or lose electrons
Charged atoms called ions are created
0 IONIC BOND Transfer of electron Na Sodium atom Cl Chlorine atom Na + Sodium ion Cl – Chloride ion Sodium chloride (NaCl) Na Cl Cl Na + – – –
Sodium and chloride ions
Bond to form sodium chloride, common table salt
An electrical attraction between ions with opposite charges
Results in IONIC BOND
Na + Cl –
join atoms into molecules through electron sharing
In covalent bonds, two atoms share one or more pairs of outer shell electrons, forming molecules
Sharing of electrons may be EQUAL or UNEQUAL
A molecule is nonpolar
When its covalently bonded atoms share electrons equally
A molecule is polar
Electrons are shared unequally between atoms, creating a polar covalent bond
are weak bonds important in the chemistry of life
The charged regions on water molecules are attracted to the oppositely charged regions on nearby molecules
Hydrogen bonding occurs in other biologically important compounds such as proteins and DNA. HYDROGEN BOND Hydrogen bond (+) (+) H H (+) (+) (–) (–) (–) (–) O
Water is the solvent of life
Polar or charged solutes dissolve when water molecules surround them, forming aqueous solutions
0 + – – – – – – – – – – + + + + + Na + + Na + Cl – Ion in solution Salt crystal Cl –
Hydrogen bonds make liquid water cohesive
Due to hydrogen bonding
Water molecules can move from a plant’s roots to its leaves by adhesion
Insects can walk on water due to surface tension
Created by cohesive water molecules
Matter consists of atoms and molecules in motion.
Kinetic Nature of Matter
Solid — have rigid shape, fixed volume. External shape can reflect the atomic and molecular arrangement.
Reasonably well understood.
Liquid — have no fixed shape and may not fill a container completely.
Not well understood.
Gas — expand to fill their container.
Good theoretical understanding.
Phases of Matter
PLASMA — an electrically charged gas; Example: the sun or any other star
BOSE-EINSTEIN CONDENSATE — a condensate that forms near absolute zero that has superconductive properties; Example: supercooled Rb gas
Other states of matter
What are some physical properties?
melting and boiling point
can be observed without changing the identity of the substance
Some physical changes would be
boiling of a liquid
melting of a solid
dissolving a solid in a liquid to give a homogeneous mixture — a SOLUTION.
Water’s hydrogen bonds regulate temperature
Water’s ability to store heat ( high heat capacity )
Moderates body temperature and climate
It takes a lot of energy to disrupt hydrogen bonds
- So water is able to absorb a great deal of heat energy without a large increase in temperature
As water cools
- A slight drop in temperature releases a large amount of heat
Water has high heat of vaporization
A water molecule takes energy with it when it evaporates
Leading to evaporative cooling
Ice is less dense than liquid water
Hydrogen bonds hold molecules in ice farther apart than in liquid water
Ice is therefore less dense than liquid water which causes it to float
Floating ice protects lakes and oceans from freezing solid
0 Liquid water Hydrogen bonds constantly break and re-form Ice Hydrogen bonds are stable Hydrogen bond
Chemical Properties and Chemical Change
Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.
Burning hydrogen (H2) in oxygen (O2) gives H2O.
Sure Signs of a Chemical Change
Gas Produced (not from boiling!)
Precipitate – a solid formed by mixing two liquids together
Physical vs. Chemical
tarnishes in air
Physical vs. Chemical
dissolving in water
burning a log
Types of Mixtures
Variable combination of 2 or more pure substances.
Heterogeneous – visibly separate phases Homogeneous – Same throughout
Chemical reactions change the composition of matter
In a chemical reaction
- Reactants interact, atoms rearrange, and products result
0 2 H2 O2 2 H2O
Synthesis: Results in the formation of new bonds and energy is required for the reaction and the product to form.
A Reactions occur when a complex nutrient is broken down in a cell to release energy for other cellular functions.
Reactions can breakdown or decompose in exchange for two new compounds
This is the general equation for photosynthesis—the process of capturing sunlight energy and converting it to chemical energy. Which of the following are the reactants of this reaction?
C 6 H 12 O 6 and O 2 .
CO 2 and H 2 O.
Acids, Bases and Salts
Life processes occur in neutral pH.
Acids, bases and salts when dissolved in water serve as electrolytes.
Salts are abundant in our body in the form of different body fluids like sweat and tears.
Importance of acids, bases and salts in living organisms
Living organisms are sensitive to acidic and basic conditions
Acid = An ionic compound that releases H + ions in solution
Base = An ionic compound that accepts H + ions or produces OH- ions in solution
Acidity is measured on the pH scale from 0 (most acidic) to 14 (most basic or alkaline)
The pH scale
The pH of most cells
Is kept close to 7 (neutral) by buffers
Buffers are substances that resist pH change
Basic solution Oven cleaner Acidic solution Neutral solution pH scale 0 1 2 3 4 5 6 7 8 9 10 11 12 Lemon juice, gastric juice Grapefruit juice, soft drink Tomato juice Human urine Pure water Human blood Seawater Milk of magnesia Household ammonia Household bleach Increasingly ACIDIC (Higher concentration of H + ) NEUTRAL [H + ]=[OH – ] H + H + H + OH – H + H + H + OH – H + H + OH – OH – H + H + OH – OH – OH – H + H + H + OH – OH – OH – OH – OH – OH – H + Increasingly BASIC (Lower concentration of H + ) OH – H + 14 13
Acid precipitation threatens the environment
Some ecosystems are threatened by acid precipitation
Acid precipitation is formed when air pollutants from burning fossil fuels
Combine with water vapor in the air to form sulfuric and nitric acids
Can kill trees and damage buildings
Are formed when an acid and a base react with one another neutralizing the concentration of H+ ions
the process is called neutralization
HCl NaOH NaCl + water + = Acid Base Salt + = NaOH Acetic Acid Sodium Acetate + water
are the elements necessary for electrochemical activity in our body.
Water (H20) – and the three minerals sodium , potassium and chloride are all necessary for the transmission of electrical impulses between cells