C CHAPTER 2 C THE ATOM What is an Atom? Atom: Smallest unit of all matter 3 Main Parts: Proton (+)...
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Transcript of C CHAPTER 2 C THE ATOM What is an Atom? Atom: Smallest unit of all matter 3 Main Parts: Proton (+)...
CCHAPTER 2
CTHE ATOM
What is an Atom?• Atom: Smallest unit of all matter• 3 Main Parts:
• Proton (+)• Neutron (0)• Electron (-)
• Protons & Electrons usually equal in number
• Elements (substance made of only 1 type of atom) are identified on the Periodic Table
Reading the Periodic Table
• Atomic Number: Number of protons the atom contains• Usually # of electrons also
• Atomic Mass: Combined # of protons and neutrons inside the nucleus• Electrons too small to affect mass
Reading the Periodic Table
• Atomic Number: Number of protons the atom contains• Usually # of electrons also
• Atomic Mass: Combined # of protons and neutrons inside the nucleus• Electrons too small to affect mass
• How many protons, electrons, and neutrons does Carbon contain?
Protons = ______
Electrons = ______
Neutrons = ______
Reading the Periodic Table
• Atomic Number: Number of protons the atom contains• Usually # of electrons also
• Atomic Mass: Combined # of protons and neutrons inside the nucleus
• How many protons, electrons, and neutrons does Carbon contain?
Protons = ______
Electrons = ______
Neutrons = ______
Reading the Periodic Table
• Atomic Number: Number of protons the atom contains• Usually # of electrons also
• Atomic Mass: Combined # of protons and neutrons inside the nucleus• Electrons too small to affect mass
• How many protons, electrons, and neutrons does Carbon contain?
Protons = ______
Electrons = ______
Neutrons = ______
6 + Neutrons = 12
Protons + Neutrons = 12
What’s the:
A) Atomic number of Beryllium?
B) Atomic mass of Beryllium?
C) How many protons?
D) How many electrons?
E) How many neutrons?
4
9
4
4
5
Atomic number = amount of protons
Atomic mass = amount of protons
+ neutrons
Atomic number = amount of protons
Atomic number = protons usually
same as electrons
Atomic mass = amount of protons
+ neutrons
•Electrons orbit the nucleus in “energy levels”1st level:
• closest to nucleus• stable w/ 2 electrons
Electron Cloud
•Electrons orbit the nucleus in “energy levels”1st level:
• closest to nucleus• stable w/ 2 electrons
2nd level:• stable w/ 8 electrons
1
2
1
2
3
4
5
6
7
8
Electron Cloud
•Electrons orbit the nucleus in “energy levels”1st level:
• closest to nucleus• stable w/ 2 electrons
2nd level:• stable w/ 8 electrons
Examine Carbon. It has 2 electrons in the first level and 4 electrons in the 2nd level. Is Carbon stable?
Electron Cloud
•Electrons orbit the nucleus in “energy levels”1st level:
• closest to nucleus• stable w/ 2 electrons
2nd level:• stable w/ 8 electrons
3rd level:• stable w/ 8 electrons
•Atoms are stable when the outermost level is “full”
1
2
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Electron Cloud
• Molecule: 2 or more atoms held together by a covalent bond• Form when atoms are unstable
• Covalent Bond: Chemical bond where atoms share electrons• Ex: Oxygen (O2)
• Why unstable? Only 6 electrons in outer energy level
Molecules8 protons8 electrons
1
2
1
2
3
4
5
6
• Molecule: 2 or more atoms held together by a covalent bond• Form when atoms are unstable
• Covalent Bond: Chemical bond where atoms share electrons• Ex: Oxygen (O2)
• Why unstable? Only 6 electrons in outer energy level
• What happens? Oxygen atom will share two electrons with neighboring oxygen atom
• End result? Both end up with 8 electrons in outer level (stable)
Molecules
• Ionic bond: chemical bond where electrons are gained/lost
• Held together by magnetic attraction
• Cause: 1 atom may steal an electron from another
• Ion: + or – charged atom
• Ex: Sodium + Chlorine = Sodium Chloride
e
e
e e
ee
ee
ee
e e
e
ee
ee
ee
ee
ee
ee
ee
e
Na atomic number = 11
Before the bonding
Cl atomic number = 17
After the bond
Na ClProtons (+)
Electrons (-)
Net charge
Na ClProtons (+)
Electrons (-)
Net charge
11+
17+11
-17-
0 0
11+
17+
10-
18-
+1 -1
Recap1) Name the 3 subatomic particles.2) Which subatomic particles are found inside the nucleus?3) The atomic number usually allows us to determine the
amount of which two subatomic particles?4) If an atom has the atomic mass of 14 and the atomic
number of 6, how many protons, neutrons, and electrons does the atom contain?
5) After an ionic bond is formed, what is the charge of the atom that gained an electron?
6) Which type of chemical bond shares electrons?
C
O
HH
WATER
Water Basics• Polar: part of a molecule is slightly positive, while another part is slightly negative
• Creates hydrogen bonds where one water sticks to another
1
1
1
2
4
3
2
1
6
5
1
1
+ +
-
Red = Oxygen (negative) White = Hydrogen (positive)
+ + + +
+
+ +
+ + +
+ +
+ +
+
+++
+ +
+ +
+
+ +
+
+
++
+ +++
+
+ +
++
+ + +
+ +
+ +
+ +
+++++++
- - -
- -
----
-
- -
-
- - - - -
----
- - - -
Water Properties
• High specific heat: Resists temperature changes• A lot of energy is needed to break
bonds between water molecules• Helps to maintain a constant body
temp (Homeostasis)
• Cohesion: polar water molecules attracted to other polar water molecules
• Adhesion: polar water sticks to other molecules
Why can this insect walk on water?
It is not heavy enough to break the bonds that hold the water molecules together.
7ml
6.8ml
Solutions• Solution: mixture where 1 substance dissolves in another
• 2 parts to a solution1) Solute: substance that dissolves• Atoms, ions, molecules
2) Solvent: substance in which the solute is dissolved in• Usually water
SUGAR
KOOL AID
Solution
Ex: Human blood• Solvent: Plasma (watery part of blood)
• Solutes: Carbs, proteins, sugars, etc…
Solutions
• pH scale measures the amount of H+ ions in a solution
• pH scale measures how acidic or basic a substance is and ranges from 0 to 14
• 1 minute: Discuss with your neighbor:A) Which base has the most H+ ions?B) Which substance has the fewest H+ ions?C) Which is the strongest acid?
pH ScaleAcid Base
neutralMore OH-
More H+ Few H+Few OH-
LemonsMilk
AmmoniaSoft drink
BloodBaking soda
blood
Ammonia
Lemons
• Some molecules release H+ ion when dissolved
• H+ ions accumulate (acids)
pH Scale
H+
H+H+H+H+H+
H+H+ H+Substance
A
Acidic solution
• Some molecules release OH- ions when dissolved
• OH- ions accumulate (bases)
OH-
OH-OH-OH-
OH-
OH-
OH- OH- OH-Substance B
Basic (alkaline) solution
pH Scale
Recap
1) Name 4 basic features of water.
2) Which water property explains that one atom is positively charged, while another is negatively charged?
3) How does cohesion and adhesion differ?
4) Which is a stronger acid? Substance A with a pH of 5 or substance B with a pH of 3?
5) Which has more H+ ions? Substance A with a pH of 5 or substance B with a pH of 3?
6) How does a solute differ from a solvent?
CORGANIC
MOLECULES
Organic Molecules• Carbon = building block of organic molecules
• Carbon is unique• Unstable: 2nd level not full• Will bond up to four times 1
2
3
4
1
2
6 protons
6 electrons
• Monomer: Small carbon molecules• Ex: Amino acid
• Polymer: chain of linked monomers• Ex: Protein
monomer
monomer
monomer
monomer
monomer
monomer
monomer
monomer
monomer
monomer
Polymer
Organic Molecules
Carbohydrates
Carbohydrates• Readily available food source
• C1: H2: O1 ratio• Ex: Glucose = C6 H12 O6
• Monomer: Monosaccharides• Simple sugars• Bond to form larger sugars
• Polymer: Polysaccharide• Complex sugars
Glucose(monosaccharide)
Fructose(monosaccharide)
Sucrose
(disaccharide)
Carbohydrate Polymers: Polysaccharide
• Polysaccharides: Long chain of monosaccharides• Ex: Starch: excess plant sugar converted & stored• Ex: Glycogen: animal starch stored in liver & muscles• Ex: Cellulose: used in plants to make cell walls
glucose
glucose
glucose
glucose
glucos
e
Recap1) How many electrons does Carbon have in the 1st energy level?
2nd energy level?
2) Which type of organic molecule is most commonly used as energy for cells?
3) What are the monomers of carbohydrates called?
4) What are the polymers of carbohydrates called?
5) Which polymer is stored by animals?
6) Which polymer is stored by plants?
Lipids
Lipid Structure• Monomer: Fatty Acid
• Polymer: Lipid
• Examples: Fats, Oils, Waxes
• Phospholipid Structure (3 parts):• “Head” of glycerol & phosphate(polar) • “Tail” of 2 fatty acids (non-polar)
• Make up the cell membrane
Phospholipid
12
Glycerol molecule
Triglyceride:
• Structure (2 parts)• “head” = glycerol• “Tail” = 3 fatty acids
• Function• Provide Energy for cells• Insulation• Cholesterol: Gives cell membrane flexibility
Lipid Structure
Saturated Fats
• Long chain of carbon bonds (all single bonds)
• Each C is “saturated” with H atoms
• Single bonds are easier to compact = solid at room temps
• Very common in animal fats
Fats and oils have different types of fatty acids.
think
Unsaturated Fats
• Long chain of carbon bonds (some double bonds)
• Double bonds• Prevent H from attaching• make “kinks”, which are not easily compacted = Liquid at room temps
• Common in Plant fats
think
Normally, blood flows freely through a vein
Blood vein RBC
Too much saturated fats…
Blood vein RBC
RBC
RBC
RBC
Cholesterol & saturated fats
Reduced circulation…Blood clots…High blood pressure
RBC
RBC
RBC
RBC
RBC
RBC
RBC
RBC
RBC
RBC
RBC
RBC
RBC
Cholesterol levels
Recap1) What are the three parts of a phospholipid?
a. Which part(s) is/are the “head”? b. Which part are the “tails”?
2) What are the two parts of a triglyceride?a. Which part(s) is/are the “head”? b. Which part are the “tails”?
3) How do saturated and unsaturated fatty acids differ?
4) Why are saturated fats less healthy?
Nucleic Acids
Nucleic Acid Basics•Contain instructions to build protein•2 typesoDNAoRNA
•Made up of smaller units called nucleotidesomonomer = nucleotideoPolymer = nucleic acid
•Nucleotides are made of three parts: •a sugar •phosphate group•nitrogen base.
- Adenine (A) - Thymine (T)- Guanine (G) - Cytosine (C)
A phosphate group nitrogen-containing molecule,called a base
deoxyribose (sugar)
Monomers link to make polymers!
Nucleotides combine to make nucleic acid!
These are the instructions for the cell to make protein.
How
man
y
Nu
cle
oti
des?
DNA• Double Helix: 2 chains of nucleotides
• DNA stores the information required to make a protein
• Gene: section of DNA that codes for a protein
RNA• 1 chain of nucleotides
• Copy the DNA code… deliver code to ribosome to create a protein
Recap1) Name the monomer of nucleic acids.
2) What are the four nitrogen bases of DNA?
3) Name the three parts to a nucleotide.
4) How are DNA and RNA different? Same?
Protein
Protein Basics• Used in variety of cellular functions
• Made of smaller amino acids• Monomer: Amino acid• Polymer: Polypeptide (Protein)
• Only 20 amino acids… but thousands of proteins• Exact arrangement of amino acids determines the protein
leucine valine glycine alanine leucine leucine histi-dine
aspara-gine serine proline = Protein A
leucinevaline glycine alanine leucine leucine histi-dine
aspara-gine serine proline = Protein B
Amino acids (monomer)
• Amino acids are linked by peptide bonds.
Enzymes• Types of proteins• Enzyme: Lowers the energy needed to start chemical reactions
• ex: Break down food• Sensitive to pH, temp can cause them to denature
• ex: If high fever: enzymes lose ability to work• Very specific in actions (lock & key)
• ex: Amylase: Breaks starch into simple sugars• Reusable
glucose glucose glucose glucose
Enzyme amylase
Starch
Recap1) What are the smaller monomers that make proteins
called?
2) How many different amino acids exist?
3) Which group of proteins help to start chemical reactions?
4) What can cause an enzyme to denature?
5) Explain the lock and key analogy as it relates to enzymes.
ENZYMES
Chemical Reactions
• Energy stored in chemical bonds• When bonds broken = Energy released (heat & light)
• Activation Energy: amount of energy needed to start a reaction
Enzymes• Catalyst: substance that decreases the activation energy needed to start a chemical reaction• Speeds up reaction
• Enzymes are catalysts in living organisms.
Enzyme Structure• Enzyme shape allows specific reactants to bind together
• Reactants = substrate• Ex: Amylase & starch: Starch is the substrate because it binds to amylase
• Substrates binds to activation sites on the enzyme (key fitting into a lock)
• Once binded to enzyme, substrates bonds break• Substrates form new bonds (product)
Recap• 1) How do enzymes speed up chemical reactions?
• 2) What is released when chemical bonds are broken?
• 3) Why is photosynthesis an example of an endothermic reaction?
• 4) Why is cellular respiration an example of an exothermic reaction?
• 5) Besides enzymes, what else is often a catalyst that speeds up reactions?
• 6) What are the molecules called that react with enzymes?
• 7) What do enzymes weaken between molecules?