Chemistry Chapter Two

What is Chemistry? Chemistry- the study of matter, atoms and chemical reactions –Why? to understand how our cells are held together To understand the molecules and compounds making up the cell Chemistry- the study of matter, atoms and chemical reactions –Why? to understand how our cells are held together To understand the molecules and compounds making up the cell

Matter Matter- anything that occupies space and has a mass –Mass- amount of matter an object has –Weight- pull of gravity on an object’s mass Weight can change, mass can not Volume- measure of the amount of space an object takes up Matter- anything that occupies space and has a mass –Mass- amount of matter an object has –Weight- pull of gravity on an object’s mass Weight can change, mass can not Volume- measure of the amount of space an object takes up

States of Matter Solid –Particles tightly linked –Definite shape –Definite volume Ice, chair, book Solid –Particles tightly linked –Definite shape –Definite volume Ice, chair, book

Liquid –Particles more loosely connected –Definite volume –Shape varies Example- water, juice Liquid –Particles more loosely connected –Definite volume –Shape varies Example- water, juice

Gas –Particles not linked at all –Volume fills whatever container it occupies –No shape Example- oxygen, helium Plasma Gas –Particles not linked at all –Volume fills whatever container it occupies –No shape Example- oxygen, helium Plasma

Atoms Atom- Basic building block of matter –Protons –Neutrons –Nucleus –Electron –Electron Cloud (energy level) aka- electron shell Atom- Basic building block of matter –Protons –Neutrons –Nucleus –Electron –Electron Cloud (energy level) aka- electron shell

Nucleus Nucleus- dense area in center of atom –Houses both protons and neutrons –Gives atoms its mass Nucleus- dense area in center of atom –Houses both protons and neutrons –Gives atoms its mass Proton- positively charged particle Neutron- particle with no charge

Nucleus of Atom

Electron Cloud Vast area of atoms in which the electrons are found moving around Electron- negatively charged particle (e-) –Found in different energy levels of cloud Vast area of atoms in which the electrons are found moving around Electron- negatively charged particle (e-) –Found in different energy levels of cloud 1st energy level- can hold max of 2 e- 2nd and up energy level- can hold max of 8 e- Valence electron- number of e- in outermost level

Electron Energy Levels

Elements Atoms with the same number of protons are the same Pure substance made of only one type of atom Atoms with the same number of protons are the same Pure substance made of only one type of atom Periodic Table- table used to organize all elements into rows and columns

Periodic Formulas Atomic number = number of protons Neutral atoms- # protons = # electrons Atomic mass= # protons + # neutrons Number of neutrons= mass- # protons –Example Argon Mass= 40, Protons= 18, Neutrons= 22 (40-18) Atomic number = number of protons Neutral atoms- # protons = # electrons Atomic mass= # protons + # neutrons Number of neutrons= mass- # protons –Example Argon Mass= 40, Protons= 18, Neutrons= 22 (40-18)

Need to Know Elements Carbon Oxygen Hydrogen Phosphorus Nitrogen Carbon Oxygen Hydrogen Phosphorus Nitrogen Sodium Magnesium Chlorine Potassium Calcium

Atomic Bonding Two or more atoms combined by a chemical bond Compound- substance formed by combining two or more different elements Two or more atoms combined by a chemical bond Compound- substance formed by combining two or more different elements Why bond? –Atoms want a complete outer shell (8 e-) –Will gain,lose or share e- to get to 8 –8 is the magic number!!!!

Types of Bonds 1. Ionic- atoms will give or gain e- –Ion- charged particle –Gain e- gives negative charge –Lose e- gives a positive charge 1. Ionic- atoms will give or gain e- –Ion- charged particle –Gain e- gives negative charge –Lose e- gives a positive charge

2. Covalent- atoms will share e- –Weaker bond because neither atom is strong enough to take e- 2. Covalent- atoms will share e- –Weaker bond because neither atom is strong enough to take e-

Van der Waals Forces In covalent bonds, some atoms have a stronger pull on the e-, so sharing is unequal This creates areas of positive and negative charges across the neutral molecule –Opposite charges then are attracted to each other

Energy Energy- ability to do work or cause change Free energy- energy available to do work Energy- ability to do work or cause change Free energy- energy available to do work

Chemical Reactions Reactants Products Reactants- atoms or compounds to start reaction Products- atoms or compounds that you end up with Reactants Products Reactants- atoms or compounds to start reaction Products- atoms or compounds that you end up with

Cont. Reactants and products are represented by atomic symbols and numbers –Number of atoms must be same on both side –Example- 2 H + OH 2 O Reactants and products are represented by atomic symbols and numbers –Number of atoms must be same on both side –Example- 2 H + OH 2 O

Cont. Arrows indicate direction of reaction indicates reaction is occurring in both directions Arrows indicate direction of reaction indicates reaction is occurring in both directions Activation energy- amount of energy needed to start a reaction –Every reaction has different amount of activation energy

Adjusting Reaction Time Catalyst- substance that lowers activation energy –Usually an enzyme Catalyst- substance that lowers activation energy –Usually an enzyme

How Enzymes Work Each has specific shape –“Lock and Key” Substrates (reactants)- bind to active site –Enzyme release product because it no longer fits Each has specific shape –“Lock and Key” Substrates (reactants)- bind to active site –Enzyme release product because it no longer fits

Factors Effecting Enzymes pH - only function in small range of pH Temperature- function best within a range Concentration Each will vary depending upon enzyme pH - only function in small range of pH Temperature- function best within a range Concentration Each will vary depending upon enzyme

Transfer of energy Transfer of energy (two types) –Exergonic- releases energy –Endergonic- absorbs energy

Reduction-Oxidation Reactions (Redox) Redox Reaction- energy transfer that includes a transfer of e- OiL RiG –Oxidation Loses –Reduction Gains

Mixtures Materials made of two or more substances that are physically mixed together, not chemically Three Types of Mixtures –Solution –Suspension –Colloid

Solutions One or more substances equally distributed in another Parts of Solution –Solute-substance that is dissolved –Solvent- substance doing the dissolving

Solutions cont. Concentration- amount of solute added to set amount of solvent –Examples- salt water, blood plasma Concentration- amount of solute added to set amount of solvent –Examples- salt water, blood plasma

Suspensions A mixture of water and particles that do not dissolve in water, but break into smaller pieces –Example, finger paint, oil and water A mixture of water and particles that do not dissolve in water, but break into smaller pieces –Example, finger paint, oil and water

Colloid Substance evenly distributed into another Can exist in solid, liquid or gas forms –Particles much smaller than suspensions Substance evenly distributed into another Can exist in solid, liquid or gas forms –Particles much smaller than suspensions

Aqueous Solution Specific type of solution in which water is always the solvent Water- known as universal solvent –All organisms need water Specific type of solution in which water is always the solvent Water- known as universal solvent –All organisms need water

Properties of Water 1.Water is bent 2.Polarity 3.Hydrogen bonds 4.Cohesion 5.Adhesion 1.Water is bent 2.Polarity 3.Hydrogen bonds 4.Cohesion 5.Adhesion

Polarity Unequal sharing of electrons –Oxygen is much larger so it steals e- –Oxygen negative charge –Hydrogen positive charge Unequal sharing of electrons –Oxygen is much larger so it steals e- –Oxygen negative charge –Hydrogen positive charge

Hydrogen Bonds Special type of bond that is formed between two different water molecules –Opposites are attracted together Special type of bond that is formed between two different water molecules –Opposites are attracted together

Cohesion- attractive force between same particles –Example- water beading, bugs walking on water Cohesion- attractive force between same particles –Example- water beading, bugs walking on water Adhesion- attractive force between unlike particles –Ex: meniscus; straw level –Also called capillary action- movement against gravity

Other Properties Freezing/melting point-0ºC Vaporization point- 100ºC Density- varies by temperature (most dense at 4ºC) Freezing/melting point-0ºC Vaporization point- 100ºC Density- varies by temperature (most dense at 4ºC)

The pH Scale What is pH? Dissociation of water- when water molecules break apart to form H+ ions and OH- ions What is pH? Dissociation of water- when water molecules break apart to form H+ ions and OH- ions pH is the measure of the amount of H+ ions in a solution Sometimes H+ will bond with H 2 O to form hydronium (H 3 O+)

Acid Vs. Base Hydroxide ion- the OH- ion Hydronium ion- the H 3 O+ Hydroxide ion- the OH- ion Hydronium ion- the H 3 O+ Acid- solution that has more H+ or H 3 O + ions Base- solution that has more OH- –Alkaline- another word for base solutions

The Scale pH scale ranges from 0-14 –Under 7= acidic –7= neutral (equal H+ and OH- ions) –Above 7= basic pH scale ranges from 0-14 –Under 7= acidic –7= neutral (equal H+ and OH- ions) –Above 7= basic Scale is logarithmic –Means every 1 number change is actually = to 10 times –Example- 7-8= 10x 7-9=100x 7-10= 1000x

pH of common items

Regulating pH Buffers- substances that neutralize small amounts of acids and bases –Important biologically for reactions to occur and to maintain homeostasis Buffers- substances that neutralize small amounts of acids and bases –Important biologically for reactions to occur and to maintain homeostasis