school biology class about Acids, Bases and pH

2. WHAT IS AN ION?
An ion is a charged atom or molecule.
It is charged because the number
of electrons do not equal the
number of protons in the atom or
molecule.
When an atom is
attracted to another atom
because it has an
unequal number of
electrons and protons,
the atom is called an ION.
If the atom has more
electrons than protons, it
is a negative ion, or
ANION. If it has more
protons than electrons,it
is a positive ion CATION.
An atom can acquire a positive charge or a
negative charge depending on the number
of electrons in an atom is greater or less
then the number of protons in the atom.

3. ACID AND BASE CONCEPTS
In Aqueous solutions, small percentage of the water
molecules themselves break apart into ions. The ions
formed are positively charged hydrogen ions (H+) and
negatively charged hydroxide ion (OH-).
For the chemical processes of life t owork correctly, the
right balance of H+ ions and OH- ions is critical.
Some chemical compounds contribute additonial H+ ions to
an aqueous solution while others remove H+ ion from it.
Hydroxide ion -
Hydrogen ion +

4. ACID AND BASE CONCEPTS
Hydroxide ion -
Hydrogen ion +

5. ACID (ACIDS)
A compound that donates H+ ions to a
solutions is called an ACID (Hydrovhloric
acid HCl in aqueous solution brakes
completely in H+ and Cl-)

6. BASE (BASES)
A compound that removes H+ ions From an
aqueous solution is called a BASE.
Some bases (sodium hydroxide NaOH), do this
by adding OH- ions, which then combine with
H+ ions and form water molecules

8. PH SCALE
Describes how acidic or basic a solution is.
Scale ranges from 0 (most acidic)
to 14 (most basic or Alkaline)
Lemon juice: ph 2
Grape juice : ph 3 ten times more H+
Neurtral : pure water or aqueous solutions that have an equal
amounts of H+ and OH- ions.
pH 7 are neither acidic nor basic.
pH of the solution inside most living cells is close to 7

9. BUFFERS
Molecules in cells are very sensitive to
concentrations of H+ and OH-
The slight change in pH can be harmful to organisms.
Many biological fluids contein BUFFERS:
Substances that cause a solution to resist changes in
pH.
A buffer works by ACCEPTING H+ ions when their
levels rise, and DONATING H+ ions when the
levels fall, thereby maintaining a fairly constant
pH in the solution.

10. AN ENVIRONMENT FIT FOR LIFE
• The abundance of the liquid water: water is needed for life
• Planets location in the solar system:far enough so it recives a
moderate quantity of energy but not so far away that
temperatures are too cold
• Ozone gas shields the planet´s surface from harmful radiation
• Availability of essential elements for life: soil rocks and
atmosphere.

11. PH ACID BASE VIDEOS
https://www.youtube.com/watch?v=RF40cI2O16U
Cabache experiment