The study of chemistry begins with the basic unit of matter, the atom ? The Greek philosopher Democritus called the smallest fragment of matter the atom, from
The branch of science that studies the preparation, properties, structure and reactions of material substances is called chemistry DEVELOPMENT OF CHEMISTRY
Chemistry is the basis for how the body transforms and uses energy and for how our cells use crucial molecules such as carbohydrates, lipids, proteins, and
Most chemical reactions in basic chemistry classes are thought of as being irreversible • isotonic solutions: Solutions containing the same osmotic pressure •
Starting with atoms it progresses to elements, molecules and compounds It shows how a substance can be simply represented by a chemical formula made up of both
Lesson 4: Basic Chemistry part 1 I Time: 50 minutes II Materials: a Handout: “Basic Chemistry part 1” b Handout: “The Periodic Table of the Elements”
2 basic concepts of chemistry 2 3 Chemical formulas and terms Relationship between configuration of valence electrons and chemical reactivity,
Note that bonds are not rigid structures, but can bend and stretch without breaking, like a spring • There are three basic types of chemical
As you will see later, this is because chemical reactions involve the rearrangement of electrons Nuclei of atoms (protons and neutrons) usually remain
UNIT 1 SOME BASIC CONCEPTS OF CHEMISTRY Chemistry is the science of molecules and their transformations It is the science not so much of the one
The study of chemistry begins with the basic unit of matter, the atom ▫ The Greek philosopher Democritus of an element have the same chemical properties
10th Edition 1 Basic Chemistry Chapter 2: pp 20-36 Chemical Elements ○ Atoms ○ Atomic Mass and Molecules and Compounds ○ Chemical Bonding
SOME BASIC CONCEPTS OF CHEMISTRY Chemistry: Chemistry is the branch of science that deals with the composition, structure and properties of matter
PDF document for free
- PDF document for free
![[PDF] BASIC CHEMISTRY](https://pdfprof.com/EN_PDFV2/Docs/PDF_8/26449_8biochemnotes.pdf.jpg "[PDF] BASIC CHEMISTRY")
26449_8biochemnotes.pdf
CH 2- THE
CHEMISTRY OF LIFE
Atoms
The study of chemistry begins with
the basic unit of matter, the atom.
The Greek philosopher Democritus
called the smallest fragment of matter the atom, from the Greek word atomos.
Atoms (cont.)
Placed side by side, 100 million atoms
would make a row only about 1 centimeter long.
Atoms contain subatomic particles that
are even smaller.
Atoms (cont.)
What three subatomic particles make
up atoms?
Atoms (cont.)
The subatomic particles that make up
atoms are
protons
neutrons
electrons
Atoms (cont.)
Smallest property of an element that still
has the properties of that element
´7OH NXLOGLQJ NORŃNV RI PMPPHUµ
Atoms are made of smaller (subatomic)
particles arranged in a particular way
p+ (proton)
n° (neutron)
e- (electron)
Atoms (cont.)
Protons and neutrons have about the
same mass.
Protons are positively charged particles
(+).
Neutrons carry no charge (Ⱥ).
Strong forces bind protons and
neutrons together to form the nucleus, which is at the center of the atom.
Atoms (cont.)
The electron is a negatively charged
SMUPLŃOH í RLPO 1C1840 POH PMVV RI M
proton.
Electrons are in constant motion in the
space surrounding the nucleus (e- cloud).
Atoms (cont.)
The subatomic
particles in a helium atom.
Atoms (cont.)
Electrons are attracted to the
positively charged nucleus but remain outside the nucleus because of the energy of their motion.
Because atoms have equal numbers of
electrons and protons, and because these subatomic particles have equal but opposite charges, atoms are neutral.
Atoms (cont.)
Atomic number- # of p+ AND electrons in an atom Mass number- total # of p+ + n° in an atom
# of neutrons- mass number- atomic number
Ion- charged atom (can gain or lose electrons) If an atom gains e-, does it have a positive or negative charge?
What if the opposite is true?
LEP-GEN (Lose Electrons Positive, Gain Electrons
Negative)
Where can the characteristics of all atoms be found?
Practice
Atomic #?
Atomic mass?
# of neutrons?
More Practice
Atomic #?
Atomic mass?
# of neutrons?
Elements
6XNVPMQŃHV POMP ŃMQ·P NH NURNHQ GRRQ LQPR VLPSOHU substances
Pure substance made of only ONE type of ATOM
Represented by one or two letter symbol (Ex. C, H,
O, Al, Fe, He, Ga, Pt, Au)
Noble gases
(OHPHQPV POMP ŃMQ H[LVP MORQH GRQ·P ŃRPNLQH RLPO RPOHU
MPRPV"XVXMOO\A
Ex. He, Ne, Ar
Mike Stanfill, Private Hand - Flash Animation - The
Elements, by Tom Lehrer
Elements (cont.)
Sodium
Reaction of Sodium with Water
Mercury
Elements (cont.)
More than 100 elements are known, but
only about two dozen are commonly found in living organisms.
Isotope
Atoms of the same element that have
GLIIHUHQP ·V RI Q
Ex. C-14 and C-12
Both have 6 p+
C-14 (8 n), C-12 (6 n)
Isotopes (cont.)
Isotopes are identified by their mass
numbers.
For example, carbon has three
isotopes³carbon-12, carbon-13, and carbon-14. Each isotope has a different number of neutrons.
Isotopes (cont.)
Q- How are all of the isotopes of an
element similar?
Isotopes (cont.)
A- Because they have the same number
of protons and electrons, all isotopes of an element have the same chemical properties.
Isotopes (cont.)
Isotopes of Carbon
6 electrons
6 protons
6 neutrons
6 electrons
6 protons
7 neutrons
6 electrons
6 protons
8 neutrons
Isotopes (cont.)
Radioactive Isotopes
Some isotopes are radioactive, meaning
that their nuclei are unstable and break down at a constant rate over time.
Although the radiation these isotopes give
off can be dangerous, they have important scientific and practical uses.
Isotopes (cont.)
Radioactive isotopes can be used:
to determine the ages of rocks and
fossils.
to treat cancer.
to kill bacteria that cause food to spoil.
MV OMNHOV RU ´PUMŃHUVµ PR IROORR POH movement of substances within an organism.
Chemical Compounds
Chemical Compounds
In nature, most elements are found
combined with other elements in compounds.
A chemical compound is a substance
formed by the chemical combination of two or more elements in definite proportions.
The physical and chemical properties of a
compound are different from the elements from which it is formed.
Chemical Compounds
Scientists show the composition of
compounds by a kind of shorthand known as a molecular formula.
Water, H2O, contains two atoms of
hydrogen for each atom of oxygen.
The formula for table salt, NaCl,
indicates that sodium and chlorine combine in a 1 : 1 ratio.
Molecular Formulas
Shows numbers of molecules and atoms
Molecules = coefficient (the number in front) of molecular formula (ex. 3H2O = 3)
Atoms = # of atoms in compound
(ex. H2O = 2 Hydrogens, 1 Oxygen = total of 3 atoms in this compound) Total # of atoms = (Coefficient) x (# of atoms)
How many molecules and atoms do each of the
following have?
3 H2O
2 C6H12O6
4 NaCl
CO2
Structural formulas
Shows how the atoms are connected in
a compound. Each element requires 1-4 lines to connect it to other atoms (see periodic table)
Ex. C2OH6
Is there a problem in drawing this?
H H | |
H - C - C - O - H
| |
H H
H H
| |
H - C - O - C - H
| |
H H
Isomers
Have same molecular formula but
different structural formulas
C3H8O
Energy shells
Located in the e- cloud
1st shell holds a maximum of 2 e-
All other shells hold up to 8 e-
Electron Configuration
Drawing of how many e- are in each orbital.
Must know atomic number so know how many
protons (and therefore how many electrons) an element has
Ex. O has atomic # of 8 therefore has 8 e-
Electron configuration = 2) 6)
Ex. Al has atomic number of 13
Electron configuration = 2) 8) 3)
Valence
Shows how elements bond together by
sharing e-
Several steps involved in determining
valence
What is an e- orbital?
How many e- can fit in each orbital?
What do we have to know before we can
determine valence?
Valence electrons
Number of e- in the outermost energy
shell
Ex. O2 has _______ valence e-
Valence (cont.)
Where are the valence e- located?
Answer: In the LAST orbital!!!
_______ +7 2) 5)
_______ +5 2) 3)
Each orbital wants to be FULL to be happy!!
To determine valence, always take the path
of least resistance (always choose the lowest number to gain or lose to make the orbital full)
Valence (cont.)
If an atom loses e-, does it become
more positive or more negative?
This positive or negative will always be
the sign in front of the valence
The valence number is found by
figuring out how many e- must be lost or gained to make the atom happy (have the last orbital full!)
Valence (cont.)
In summary, to find valence:
1.Look up the atomic number (# of p+)
2.Determine the electron configuration
3.Determine the # of valence e- (# of electrons
in last shell)
4.Determine if it is + or ² valence (if it gains e- it
becomes more negative and vice versa)
5.Determine valence by how many e- it would have
to lose or gain to be happy
Valence (cont.)
Want an easier way to find valence?
Label your periodic table!
Chemical bonds
Forces that hold atoms together
Can be single, double, or triple bond
Depends on how many pairs of electrons
are shared between elements
Single bond
Double bond
Triple bond
Bond Lines
All elements have the ability to bond
with other element(s)
Can have anywhere between 1 and 4
bond lines
How do we know how many bond lines
each element has?
Answer: the number of bond lines is the
same of the valence of the element (without the + or ² sign)
Bonding (cont.)
Ex. Cl has a valence of -1, so it has one
bond line.
Ex. C has a valence of ±4, so it has four
bond lines.
Ex. N has a valence of -3, so it has
three bond lines.
Bonding rules
Each element must have the correct #
of bond lines attached to it
# of bond lines is determined by
_________?
Ex. O2 has valence of -2, so it has
_________ bond lines.
Ex. C has a valence of ± 4, so it has
_________ bond lines.
Bonding rules (cont.)
All coefficients and subscripts must be
satisfied.
Ex. 2C2H6- Must draw two molecules
each having 2 carbons and 6 hydrogens
Changing molecular formulas
to structural formulas
All bond lines, subscripts, and
coefficients must be satisfied.
Ex. H2O
Changing structural formulas
to molecular formulas
All coefficients and subscripts must be
satisfied.
Ex. H ² O ² + ȴ! +2O
Ex. H ² Cl H ² FO ȴ! 2+FO
Types of bonds
Covalent
Chemical bonding where pairs of electrons are shared Strongest type of bond (gets stronger as more pairs of electrons are shared)
Polar covalent bond
Present in water molecules
Because electronegativity difference between O and H, a bond forms where the O has a partial negative charge and H a partial positive charge
Types of bonds
Ionic bond
Weak bond formed between two
oppositely charged ions
Type of bonds in salt (NaCl)
Hydrogen bond
Caused when hydrogen and an
electronegative atom bond
Weakest type of bond
Organic compound
Must contain carbon (C)
Usually associated with living things
Ex. Carbohydrates, lipids, proteins,
nucleic acids
What is inorganic????
Chemical Bonds
What are the two main types of
chemical bonds?
Chemical Bonds
The main types of chemical bonds are:
ionic bonds
covalent bonds
Chemical Bonds
Chemical Bonds
The atoms in compounds are held together
by chemical bonds.
Bond formation involves the electrons
that surround each atomic nucleus.
The electrons that are available to form
bonds are called valence electrons.
Chemical Bonds
Ionic Bonds
An ionic bond is formed when one or more
electrons are transferred from one atom to another.
An atom that loses electrons has a
positive charge.
An atom that gains electrons has a
negative charge.
These positively and negatively charged
atoms are known as ions.
Chemical Bonds
Protons +17
Electrons - 18
Charge -1
Protons +11
Electrons - 11
Charge 0
Protons +11
Electrons - 10
Charge +1
Protons +17
Electrons - 17
Charge 0
Chloride ion (Cl-)
Sodium atom (Na) Chlorine atom (Cl)
Sodium ion (Na+)
Chemical Bonds
Covalent Bonds
Sometimes electrons are shared by atoms
instead of being transferred.
Sharing electrons means that the moving
electrons actually travel in the orbitals of both atoms.
Chemical Bonds
A covalent bond forms when electrons
are shared between atoms.
When the atoms share two electrons, the
bond is called a single covalent bond.
When atoms share four electrons it is
called a double bond.
When atoms share six electrons it is
called a triple bond.
Chemical Bonds
The structure that results when atoms
are joined together by covalent bonds is called a molecule.
A molecule is the smallest unit of most
compounds.
Chemical Bonds
In a water
molecule, each hydrogen atom forms a single covalent bond with the oxygen atom.
Chemical Bonds
Van der Waals Forces
When molecules are close together, a
slight attraction can develop between the oppositely charged regions of nearby molecules.
Chemists call such intermolecular forces
of attraction van der Waals forces, after the scientist who discovered them.
Chemical Bonds
Although van der Waals forces are not
as strong as ionic bonds or covalent bonds, they can hold molecules together, especially when the molecules are large.
Chemical Bonds
For example, van der
Waals forces form
between the molecules on
POH VXUIMŃH RI M JHŃNR·V
foot and the molecules on the surface of the wall.
The combined strength of
all the van der Waals forces allows the gecko to grip the wall. 2-1
The particles that move around the
nucleus of an atom are called
neutrons.
protons.
electrons.
isotopes.
2-1
The atomic number of a carbon atom is 6.
How many neutrons does the isotope
carbon-14 have?
6
8
12
14
2-1
Which of the following statements about
the three isotopes of carbon is true?
They are all radioactive.
They have different numbers of electrons.
They have the same chemical properties but
differ in atomic mass.
They have the same number of protons and
neutrons. 2-1
A chemical compound consists of
electrons mixed with neutrons.
two or more elements combined in a definite
proportion.
two or more elements combined in any
proportion.
at least three elements combined by ionic or
covalent bonds. 2-1
Van der Waals forces are the result of
unequal sharing of electrons.
ionic bonds.
the bonding of different isotopes.
the chemical combination of sodium and
chlorine.
Basic Chemistry Documents PDF, PPT , Doc