C CHAPTER 2 C THE ATOM What is an Atom? Atom: Smallest unit of all matter 3 Main Parts: Proton (+)...

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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

• How many protons, electrons, and neutrons does Carbon contain?

Protons = ______

Electrons = ______

Neutrons = ______

• Atomic Mass: Combined # of protons and neutrons inside the nucleus

Protons = ______

Electrons = ______

Neutrons = ______

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?

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

2nd level:• stable w/ 8 electrons

Electron Cloud

Examine Carbon. It has 2 electrons in the first level and 4 electrons in the 2nd level. Is Carbon stable?

Electron Cloud

3rd level:• stable w/ 8 electrons

•Atoms are stable when the outermost level is “full”

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

• 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

Na atomic number = 11

Before the bonding

Cl atomic number = 17

After the bond

Na ClProtons (+)

Electrons (-)

Net charge

Na ClProtons (+)

Electrons (-)

Net charge

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?

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

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.

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

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

Ammonia

Lemons

• Some molecules release H+ ion when dissolved

• H+ ions accumulate (acids)

pH Scale

H+H+H+H+H+

H+H+ H+Substance

Acidic solution

• Some molecules release OH- ions when dissolved

• OH- ions accumulate (bases)

OH-OH-OH-

OH- OH- OH-Substance B

Basic (alkaline) solution

pH Scale

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

6 protons

6 electrons

• Monomer: Small carbon molecules• Ex: Amino acid

• Polymer: chain of linked monomers• Ex: Protein

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

glucos

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

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.

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

Normally, blood flows freely through a vein

Blood vein RBC

Too much saturated fats…

Blood vein RBC

Cholesterol & saturated fats

Reduced circulation…Blood clots…High blood pressure

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.

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?

C CHAPTER 2 C THE ATOM What is an Atom? Atom: Smallest unit of all matter 3 Main Parts: Proton (+)...

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