Post on 06-Oct-2020
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Basic Chemistry
What is Matter?
Matter is anything that has mass and takes
up space.
Matter can be found in 4 distinct phases:
solid, liquid, gas, and plasma.
Matter is composed of small units called
atoms.
What is an Atom?
An atom is the basic
unit of matter.
It is composed of
negatively charge
electrons spinning
around a nucleus
containing positively
charged protons and
non charged neutrons.
Atomic Number and Atomic
Mass
The atomic number of an atom is the
number of protons it contains in its
nucleus.
Sometimes it may also equal the number of
its electrons.
The atomic mass of an atom is the total
number of its protons and neutrons.
Chemical Elements
Atoms have been grouped according to their
atomic number and mass into units called
elements.
Elements are substances that are made up of only
one type of atom.
~ 92 natural elements exist.
These elements are represented by symbols.
The Periodic Table contains the complete list of
these elements.
Chemical Elements
The number of neutrons is equal to the atomic
mass minus the atomic number.
An isotope is an atom of the same element with
the same number of protons but a different
number of neutrons
Elements in Organisms
Living organisms are extremely diverse but
must obey chemical and physical laws.
C HOPKINS CaFe MgCl
Periodic Table
Chemical Compounds
Are formed when 2 or
more different
elements combine.
The upper example is
a molecule of glucose
while the lower one is
2 water molecules.
What Holds Chemical Compounds
Together?
Atoms need to be stable.
In order for this to occur they must completely
fill their outer level of electrons.
This usually requires 8 (H and He only need 2).
Most atoms are lacking anywhere from 1 to 7
electrons.
Sodium is lacking ________
Chlorine is lacking _______
Periodic Table
Types of Chemical Bonds
Ionic
Covalent
Van der Waals Forces
Hydrogen bonds (we will discuss later)
Ionic Bond
This type of bond is formed when one element takes the electron it needs from another element.
This causes one element to become a + ion (called a cation) due to the loss of its electron and the other a negative – ion (called an anion)due to the gain of the electron.
The bond is formed by the attraction of the + element to the - element.
Example: Na+ + Cl- = NaCl
Ionic Bond
Na Cl
Covalent Bond
This type of bond is formed by the
sharing of electrons between different
atoms.
It is a strong bond.
Examples: 2H2 + O2 ----> 2H2O
Covalent Bond
H H
O
Polar Covalent bonds
Covalent bonds where electrons are not
shared equally are called polar covalent
bonds
This is determined by the
electronegativity of the atoms in the
bond
Electronegativity is a measure of the
attraction of an atom for electrons in a
covalent bond.
Van der Waals Forces
Rapid movements of electrons can create
regions that have a tiny positive or negative
charge
Slight attractions can develop between
oppositely charged regions of nearby
molecules
Structural Formula
What is the C in the
compound Alanine?
What is the line
represent between the
C and C?
What does the 2 and 3
represent?
Chemical Reactions.
2H2 + O2 ----> 2H2O
Chemical reactions like the one above
contain two parts: The reactants and the
products.
The reactants are on the left of the arrow,
while the products are to the right.
What is pH?
pH is the negative log of the Hydrogen ions concentration in solution.
Water’s chemical formula is H2O. Or
H-O-H.
Water has the ability to split into 2 separate ions: H+ and OH-.
If these ions are in balance than the solution’s pH is neutral or 7.
pH Scale
The pH scale is based on the number 10.
7 is the middle or neutral.
Acids contain more H+ in solution than the OH-
ions. Any number below 7 is considered acidic.
Bases contain more OH- ions than H+ ions. Any
number higher than 7 is considered a base.
pH is a very important variable in all chemical
reactions.
pH Scale
Problems
If stomach acid has a pH of 1, and a person
took a tums tablet which raised the pH to 3,
how much was the increase in pH?
What is acid rain?
How would we make an acidic lake normal
again?