Ch 2

Chemistry- properties & the transformations (chemical reactions) of all forms of matter

Matter is ….anything that takes up space or has mass.

Matter is made of elements.

How are atoms studied?

• Atoms smallest unit of matter “indivisible

• Atoms too small in size to study easily

• Size of Earth : soda can = soda can : atom

Who studied the atom?

• Studied by many scientists for centuries– Democritus (400 BC) – phrase “atomos”– Rutherford (1911) – nucleus (gold foil expt)– Moseley (1913) – X-rays to find atomic #– *Bohr (1913) – planetary model of the atom– *Schrödinger (1923) – electron cloud

model

What is the structure of an atom?

Bohr Model

“Planetary Model”

Structure• Nucleus – center of atom

– Protons and Neutrons

1. Proton–positive (+) charge–relative mass 1–Determines atomic number

2. Neutron• no (0) charge• relative mass 1• Determines isotope

–Isotopes are two of the same element with different masses (and diff # of neutrons)

3. Electron– negative (-) charge

– relative mass of 0 (zero)

– Determines ion

– Found outside the nucleus• Bohr model – electrons are in specific

energy levels

Electron shells

• determine how atom behaves when encounters other atoms

• Valence shell- outer shell

• Placed according to rules• 1st shell holds up to 2 electrons• Each shell after can hold up to 8• Most stable octet rule- 8 in valence shell

Structure of Atoms

Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons

C would like to N would like toO would like to

Gain 4 electronsGain 3 electronsGain 2 electrons

Element-

• Pure substance, one type of atom

• Represented with symbol(s)

Atomic number equals the number of ____________ ________________.Atomic mass equals the number of ______________ + .

Atomic NumberSymbolNameAtomic Mass

protons

protons neutrons

How are P, N, e- related?

• # protons = atomic number

• # electrons = # protons in a neutral atom

• # protons + # neutrons = atomic mass

• # neutrons=atomic mass -atomic number

Electron Dot Structures

Symbols of atoms with dots to represent the valence-shell electrons

1 2 13 14 15 16 17 18

H He:

Li Be B C N O : F :Ne :

Na Mg Al Si P S :Cl :Ar :

Compound- substance formed when two or more elements combine

Molecule- smallest particle of a compound

IONIC BOND- giving and taking of electrons- forms ions- charged particles

Covalent Bond

• Sharing of electrons

Non-polar covalent bond – equal sharing of electrons

Polar covalent bond – unequal sharing of electrons ex. water

Bonding

Covalent bonding

Polar covalent bond

Hydrogen Bond

• Weak chemical attraction between polar molecules (water molecules)

Water – Chapter 2.3

Properties of Water

• Transparent• Universal solvent• Cohesion and adhesion• High heat capacity• High boiling point• Evaporative Cooling• Less Dense as ice/solid

1. Transparent

• Light passes through (reach aquatic plants)

Solute – substance dissolved in a solvent forms solution

Solvent – fluid that dissolves solutes

ex. Substances dissolved in blood

2. Solvent of Life- many compounds dissolve in water

- Cohesion- Water molecules stick together due to H bonds- Adhesion- Stick to other molecules

3. Cohesion and Adhesion

capillary action- water pulled to top of trees (adhesion)

4. High Heat Capacity

- Takes a lot of energy to raise the temp of water because h bonds

- helps maintain body temp

Water is cooling!Do I look

cool?

5. High Boiling Point

• A lot of energy needed to pull apart water molecules, rare when boiling occurs in nature

6. Evaporative Cooling• The cooling of a

surface occurs when liquid evaporates

– Moderating earth’s climate

– Preventing overheating

Molecules spread apart as temp goes down

- or all aquatic animals would die in winter

7. Less Dense as solid

So can you name all of the properties of water?

TransparentAdhesion

Cohesion

capillary action

high surface tension

holds heat to regulate temperature (High heat capacity)High Boiling PointEvaporative Cooling

less dense as a solid than a liquid

Restate Questions

• Pg 30 1-3

• And pg 33 1 and 2

Acids and BasesAcids and BasesAcids and BasesAcids and Bases

Acids

Taste Sour

pH less than 7

Corrode metals (produce H gas with some metals)

Neutralize bases

Turns blue litmus paper red “Blue to Red A-CID”

Turn bromthymol blue to yellow

Bases

• Taste bitter, chalky• pH greater 7• Turn litmus paper blue• Turn bromthymol blue to blue “basic blue”• Slippery to touch• Neutralize acids• Many soaps, antacids

Acids and BasesStrength compared using pH scale

Ranges from 0 – 14

Acid – donates H+ to the solutionRanges from pH 0-6.9

Base – removes H+ from the solution by donating OH-

Ranges from pH 7.1 – 14

Distilled water is pH 7.0 or neutral. Why?

H2O H+ + OH-

Chapter 2 Chemical Principles

Chapter 2 Chemical Principles

Acids and Bases

Neutralization- reaction b/n acids and bases

• Remaining ions from acid and base combine to form a salt

• Salt- any substance formed along w/water in a neutralization reaction.

• come up with 7 questions that would be good on the test over chapter 2.

• High Order thinking

• At most four multiple choice

Cells and Nutrition

• nutrients- chemicals that organisms use for energy

development, growth, and tissue repair

• Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur made up 98% mass of living organisms (CHNOPS)

A. Carbohydrates (sugars and starches)

1. Simple Sugars- monosaccharide- made of one sugar molecule. ex glucose

2. Complex Sugars- disaccharide, ex Sucrose (table sugar) made of two simple sugars. glucose and

fructose3. Starches- polysaccharide (poly= many) made up of long chains of simple sugar molecules combined together

B. Lipids

• when body has excess carbs converts to fats.

- fats store energy more efficiently than carbs

- make up part of the plasma membrane

- include oils, waxes, steroids, and other water insoluble organic compounds

C. Protein

• composed of long chains of amino acids• 20 different types of amino acids in humans

Two functions 1. Build types of tissue - and repair of cell

a. ex cartilage tendons made of collagen

b. hair and nails made of a different protein called keratin

c. proteins in the cell membrane

2. Regulate rate which chemical reactions take place by acting as enzymes

-made in ribosomes-amino acids connected to make specific proteins.

-blueprint stored in DNA

D. Nucleic Acids

• - Two types of nucleic acids DNA and RNA

•

1. DNA- Deoxyribonucleic acid- double strand of nucleotides (double helix)

- Long chain of nucleotides (3 parts)a) sugar (deoxyribose= DNA) b) phosphate groupc) base - one of four

1. adenine (A)2. thymine (T) 3. cytosine (C)4. guanine (G)

- A pairs with T- G pairs with C

2. RNA Ribonucleic acida) sugar (ribose)b) phosphate groupc) base

1. adenine (A)2. uracil (U)3. cytosine (C)4. guanine (G)

- A pairs with U- G still pairs with

C

Homework

• PG 33 # 3

• Pg 37 1,3,4,5

2.4 Energy and Chemical Reactions

• Organisms need Energy for Life Processes (stored, power metabolism, build cell structures)

• Energy- ability to do work

Examples- Light- radiant energy in waves- Heat- molecular motion of matter ex. Rubbing hands

- Chemical- stored because of chem makeup

- electrical energy- electrons through a conductor

- mechanical energy- moving objects perform work ex. Sound, pedals turning bike

energy can be stored or released by chemical

reactions- chem bonds broken and new

formeda) Reactants =starting materials in chem reaction

b) Products = newly formed substances

Reactants------> ProductsNaCl---> Na+ + Cl-

- activation energy - energy needed to start a reaction

•metabolism- all chemical reaction occur in a organism

- get most energy from food

Enzymes (protein)- increase speed of chemical

reactions- most proteins- act as catalysts- reduce

activation energy - Helps maintain homeostasis- allows body to breakdown CO2

quickly- only bind to certain substrates***Temperature and pH affect

enzyme activity *

Homework Restate

• PG 42 1-3