1.Which four elements are the most common in living things? 2. What do you know about these four elements?

1. Which four elements are the most common in living things?

2. What do you know about these four elements?

The Life of a Cell

The Chemistry of Life

Atoms and Their Interactions

• Element: a substance that can’t be broken down into simpler chemical substances. It is made of one type of atom.

ElementsElements• Everything – whether it is a rock, frog, or

flower – is made of substances called elements.

• Of the naturally occurring elements on Earth, only about 25 are essential to living organisms.

• Carbon, hydrogen, oxygen, and nitrogen make up more than 96 percent of the mass of a human body.

Natural elements in living thingsNatural elements in living things

Trace elementsTrace elements

• Trace elements such as iron and copper, play a vital role in maintaining healthy cells in all organisms.

• Plants obtain trace elements by absorbing them through their roots; animals get them from the foods they eat.

Table 6.1 Some Elements That Make Up the Human Body

Element SymbolPercent By Mass in Human Body


Molybdenum

Oxygen

CarbonHydrogen

Nitrogen

Calcium

Phosphorus

Potassium

Sulfur

Sodium

Chlorine

Magnesium

Selenium

IronZinc

CopperIodine

ManganeseBoron

Chromium

Cobalt

Fluorine

OC

H

N

Ca

P

K

S

Na

Cl

Mg

65.018.5

9.5

3.3

1.5

1.0

0.4

0.3

0.2

0.2

0.1

Fe

Zn

CuI

Mn

B

Cr

Mo

Co

Se

F

trace

trace

tracetrace

trace

trace

tracetrace

trace

trace

trace

• Atom: the smallest particle of an element that has the characteristics of that element.

Atoms: The Building Blocks of ElementsAtoms: The Building Blocks of Elements

• Atoms are the basic building blocks of all matter.

• All nuclei contain positively charged particles called protons (p+) and particles with no charge, called neutrons (n0).

• Nucleus: the center of an atom

The structure of an atom

The Structure of an atom

Nucleus

Electron energy levels

• The region of space surrounding the nucleus contains extremely small, negatively charged particles called electrons (e-)

• This region of space is referred to as an electron cloud.

The Structure of an atom

• Protons and neutrons are approximately the same size and mass, at around 1 AMU.

• Electrons are far smaller, and they are 1⁄1836 the size of protons and neutrons

• Because opposites attract, the negatively charged electrons are held in the electron cloud by the positively charged nucleus.


• Electrons exist around the nucleus in regions known as energy levels.

Nucleus8 protons (p+)8 neutrons (n0)

Oxygen atom


• An atom of fluorine has nine electrons. How many electrons are in its second energy level?

• The first energy level can hold only two electrons. The second level (there are two of these) can hold a maximum of eight electrons. The third level can hold up to 18 electrons.


• Atoms contain equal numbers of electrons and protons; therefore, they have no net charge.

• If an atom of fluorine has nine electrons, how many protons are in an atom of fluorine?

• Atoms of the same element always have the same number of protons but may contain

different numbers of neutrons.

Isotopes of an ElementIsotopes of an Element

• Isotopes: atoms of the same element that have different numbers of neutrons• Carbon-12, carbon-13 and carbon-14 are examples of isotopes.

• Compound: a substance that is composed of atoms of two or more different elements that are chemically combined.

Compounds and BondingCompounds and Bonding

• Table salt (NaCl) is a compound composed of the elements sodium and chlorine.

Chemical formula

• Atoms combine with other atoms only when the resulting compound is more stable than the individual atoms.

How covalent bonds formHow covalent bonds form

• For many elements, an atom becomes stable when its outermost energy level is full.

• Sharing electrons with other atoms is one way for elements to

become stable.

• Two hydrogen atoms can combine with each other by sharing their electrons.


• Each atom becomes stable by sharing its electron with the other atom.

Hydrogen molecule

How covalent bonds formHow covalent bonds form• The attraction of

the positively charged nuclei for the shared, negatively charged electrons holds the atoms together.

Hydrogen molecule

• Covalent bond : an attractive force between two atoms that share electrons.


• Molecule : a group of atoms held together by

covalent bonds. It has no overall charge.

Water molecule

• An atom (or group of atoms) that gains or loses electrons has an electrical charge and is called an ion.

• Ion: a charged particle made of atoms.

How ionic bonds formHow ionic bonds form

• Ionic bond : attractive force between two ions of opposite charge

• Example: A chlorine atom becomes a chloride ion when it gains an electron.

• Chemical reactions occur when bonds are formed or broken, causing substances to recombine into different substances (ex.

burning paper).

Chemical ReactionsChemical Reactions

• Metabolism : all of the chemical reactions that occur within an organism

• In a chemical reaction, substances that undergo chemical reactions, are called reactants.

Writing chemical equationsWriting chemical equations

• Substances formed by chemical reactions, are called products.

• A molecule of table sugar can be represented by the formula: C12H22O11.

•How many atoms are in a molecule of table sugar (sucrose)?

Writing chemical equationsWriting chemical equations

• The easiest way to understand chemical equations is to know that atoms are neither

created nor destroyed in chemical reactions. They are simply rearranged.

• Mixture : a combination of substances in which the individual components retain their

own properties.

Mixtures and SolutionsMixtures and Solutions

• Neither component of the mixture changes.

• Solution : a mixture in which one or more substances (solutes) are distributed evenly in

another substance (solvent).

Mixtures and SolutionsMixtures and Solutions

• Sugar molecules in a powdered drink mix dissolve easily in water to form a solution.

• Chemical reactions can occur only when conditions are right.

Acids and basesAcids and bases

• A reaction may depend on:- energy availability- temperature- concentration of a substance

- pH of the surrounding environment

• pH : a measure of how acidic or basic a solution is.


• A scale with values ranging from below 0 to above 14 is used to measure pH.

More acidic Neutral More basic

• Substances with a pH below 7 are acidic.

•Acid : any substance that forms hydrogen ions (H+) in water


• A solution is neutral if its pH equals seven.

More acidic Neutral More basic

• Substances with a pH above 7 are basic.

•Base : any substance that forms hydroxide ions (OH-) in water.


pH 11

Question 1

Which of the following is an element?

D. water

C. sodium chloride

B. carbon

A. chlorophyll

The smallest particle of an element that has the characteristics of that element is a(n) __________.

Question 2

D. atom

C. nucleus

B. electron

A. proton

Which of the following can contain two types of particles?

D. electrons

Question 3

B. protons

C. neutrons

A. nucleus

Question 4

B. Sodium and chlorine atoms have no overall electrical charge.

A. Sodium and chlorine are sharing electrons in their outer energy levels.

Sodium and chlorine combine to form table salt. What do you know to be true?

Question 4

D. Sodium and chlorine atoms in table salt have full outer energy levels.

C. Sodium and chlorine are less stable in the compound sodium chloride.

Sodium and chlorine combine to form table salt. What do you know to be true?

Question 5

What is it called when atoms share electrons?

D. diffusion

C. hydrogen bonding

B. ionic bonding

Water molecule

A. covalent bonding

Question 6

Which of the following combinations will produce a solution?

D. oil and vinegar

C. powdered drink mix and water

B. sand and sugar crystals

A. chocolate chips and cookie dough

Question 7

What type of substance forms hydrogen ions in water?

D. polar

C. base

B. acid

A. enzyme

Question 8

Which of the following best describes a molecule with an unequal distribution of charge?

D. diffuse

C. basic

B. acidic

A. polar

Question 9

An oxygen atom has 8 protons and 8 neutrons. How many electrons does it have?

D. 0

C. 32

B. 18

A. 8

Question 10

What is the difference between a compound and an element?

# 1 Answer

The answer is B. An element can't be broken down into simpler chemical substances. Chemical elements combine in different ways to form a variety of substances useful to living things.

Table 6.1 Some Elements That Make Up the Human Body



Molybdenum

Oxygen

CarbonHydrogen

Nitrogen

Calcium

Phosphorus

Potassium

Sulfur

Sodium

Chlorine

Magnesium

Selenium

IronZinc

CopperIodine

ManganeseBoron

Chromium

Cobalt

Fluorine

OC

H

N

Ca

P

K

S

Na

Cl

Mg

65.018.5

9.5

3.3

1.5

1.0

0.4

0.3

0.2

0.2

0.1

Fe

Zn

CuI

Mn

B

Cr

Mo

Co

Se

F

trace

trace

tracetrace

trace

trace

tracetrace

trace

trace

trace

#2 Answer

The answer is D. Atoms are the basic building blocks of all matter and have the same general structure, including a nucleus and electrons. Elements found in both living and nonliving things are made of atoms.

Nucleus


An atom has a nucleus and electrons in energy levels.

# 3 Answer

The answer is A. The nucleus is the center of the atom and may contain both positively charged particles and particles that have no charge.


Oxygen atom

#4 Answer

The answer is D. Sodium and chlorine atoms combine because the resulting compound, table salt, is more stable than the individual atoms. Sodium loses an electron in its outer energy level, chlorine gains that electron in its outer energy level, and an ionic bond is formed.

#5

The answer is A. Covalent bonds differ from ionic bonds in that the shared electrons move about the nuclei of both atoms of the covalent compound. Water

molecule

# 6

The answer is C. All of the combinations are mixtures because the individual components retain their own properties. A solution is a mixture in which one or more substances is dissolved in another and will not settle out of solution.

Water molecules

Sugar molecules

Sugar crystal

# 7

The answer is B. Any substance that forms hydrogen ions (H+) in water is an acid. The pH of a substance is a measure of how acidic or basic a solution is.

#8

The answer is A. Each polar molecule has a positive end and a negative end. Polar water molecules attract ions and other polar molecules, and can dissolve many ionic compounds.

#9

The answer is A. Atoms contain equal numbers of electrons and protons and have no net charge.


Oxygen atom

• # 10 Answer• A compound is a substance that is composed

of atoms of two or more different elements that are chemically combined. An element is a substance that can't be broken down into simpler chemical substances

1. What are some characteristics of water?2. How do organisms use water to live and grow?

The Life of a Cell


Water and Diffusion

• Water is perhaps the most important compound in living organisms.

Water and Its ImportanceWater and Its Importance

• Water makes up 70 to 95 percent of most organisms.

Water is Polar

• Sometimes, when atoms form covalent bonds they do not share the electrons equally. This is called a polar bond.

Water is Polar

• Polar molecule : a molecule with an unequal distribution of charge; that is, each molecule has a positive end and a

negative end.

• Water is an example of a polar molecule.

• Water can dissolve many ionic compounds, such as salt, and many other polar molecules, such as sugar.

Water is Polar

• Water molecules also attract other water molecules.

• Weak hydrogen bonds are formed between positively charged hydrogen atoms and negatively charged oxygen atoms.

Hydrogen atom

Hydrogen atom

Oxygen atom

• Water resists changes in temperature. Therefore, water requires more heat to increase its temperature than do most other common liquids.

•Water can move UP because of capillary action.

Unique properties of water

Unique properties of water

• Water is one of the few substances that expands when it freezes.

• Ice is less dense than liquid water so it floats as it forms in a body of water.

Early observations: Brownian motion • In 1827, Scottish scientist Robert Brown used a

microscope to observe pollen grains suspended in water. He noticed that the grains moved constantly in little jerks, as if being struck by invisible objects.

• This motion is now called Brownian motion.

• Today we know that Brown was observing evidence of the random motion of atoms and molecules.

The process of diffusion

• Diffusion : the net movement of particles from an area of higher concentration to an area of lower concentration.

• Diffusion results because of the random movement of particles (Brownian motion).

• Three key factors—concentration, temperature, and pressure—affect the rate of diffusion.

The results of diffusion

• When a cell is in dynamic equilibrium with its environment, materials move into and out of the cell at equal rates.

•As a result, there is no net change in concentration inside or outside the cell.

Material moving out of cell equals material moving into cell

Diffusion in living systems • The difference in concentration of a substance

across space is called a concentration gradient.

• Ions and molecules diffuse from an area of higher concentration to an area of

lower concentration, moving with the gradient.• Dynamic equilibrium occurs when there

is no longer a concentration gradient.

Diffusion in living systems • Diffusion continues until there is no longer a

concentration gradient and dynamic equilibrium has been reached.

1. Explain why water is important to living organisms.

2. Define diffusion in your own words

3. Explain what dynamic equilibrium means

Answers1. Living organisms must have water for life

processes, because critical molecules and ions must be free to move and collide, which only happens when they are dissolved in water. Water also transports materials in living organisms, such as in blood or sap.

2. Diffusion is the movement of particles from high concentration to low concentration

3. Dynamic equilibrium happens when an equilibrium of particles exist between the gradient

Bellwork 9/9/15

• Get out your vocabulary • Add the following prefix to your prefix/suffix

sheet:Macro— Large

Your quiz on the 10 pre/suffixes will be Friday!

The Life of a Cell


Life Substances

• Carbon compounds that come from living organisms are called organic compounds.

• A carbon atom has four electrons available for bonding in its outer energy level.

• In order to become stable, a carbon atom forms four covalent bonds that fill its outer energy level.

The Role of Carbon in Organisms

The Role of Carbon in Organisms

• Two carbon atoms can form various types of covalent bonds—single, double or triple.

Single Bond Double Bond Triple Bond

• Carbon compounds vary greatly in size.

Molecular chains

• When carbon atoms bond to each other, they can form straight chains, branched chains, or rings.

Molecular chains • Small molecules bond together to form

large chains called polymers.

• Polymer : a large molecule formed when many smaller molecules bond together.

• Polymers usually form by covalent bonding.

The four major macromolecules

• Carbohydrates• Lipids• Nucleic Acids• Proteins

• Carbohydrate : a biomolecule composed of carbon, hydrogen, and oxygen with a ratio of 2 hydrogen atoms and 1 oxygen atom for every 1 carbon atom.

The structure of carbohydrates

• Glucose and fructose combine in a condensation reaction to form sucrose (table sugar)


• Monosaccharide : the simplest type of carbohydrate; a simple sugar (ie. glucose, fructose)

• The largest carbohydrate molecules are polysaccharides, polymers composed of many monosaccharide subunits. (ie. potatoes, liver)


• Plant energy is stored in the form starch, animal energy is stored in the form of glycogen

• Lipids : large biomolecules that are made mostly of carbon and hydrogen with a small amount of oxygen. (ie. fats, oils, waxes)

The structure of lipids


• They are insoluble in water because their molecules are nonpolar and are not attracted by water molecules.

• A fatty acid with single bonds is saturated; with double bonds is unsaturated


• Protein : a large, complex polymer composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.

The structure of proteins

The structure of proteins • Amino acids : the basic building blocks of

proteins • There are about 20 common amino acids that

can make literally thousands of proteins.

• Peptide bonds : covalent bonds formed between amino acids.


• Proteins are the building blocks of many structural components of organisms.


The structure of proteins • Enzymes are important proteins found in

living things.

• Enzyme : a protein that changes the rate of a chemical reaction.

• They speed the reactions in digestion of food.

• Nucleic acid : a complex biomolecule that stores cellular information in the form of a code.

The structure of nucleic acids

• Nucleotides : small subunits that make up nucleic acids

The structure of nucleic acids • Nucleotides are arranged in three groups—a

nitrogenous base, a simple sugar, and a phosphate group.

Phosphate

SugarNitrogenous

base

• DNA, which stands for deoxyribonucleic acid is a nucleic acid.

The structure of nucleic acids

Phosphate

SugarNitrogenous

base

The structure of nucleic acids • The information coded in DNA contains the

instructions used to form all of an organism’s enzymes and structural proteins.

• Another important nucleic acid is RNA, which stands for ribonucleic acid. RNA is a nucleic acid that forms a copy of DNA for use in making proteins.

• What is a polymer?

• How many types of bonds does Carbon make?

• What is a Carbon Compound?

Draw a mark at the midpoint of a sheet of paper along the side edge.

To return to the chapter summary click escape or close this document.

Then fold the top and bottom edges in to touch the midpoint.

Fold in half from side to side.


Open and cut along the inside fold lines to form four tabs.


Label each tab.


How many covalent bonds does a carbon atom need to form in order to become stable?

Question 1

D. 4

C. 3

B. 2

A. 1

A __________ is a biomolecule composed of carbon, hydrogen, and oxygen with a ratio of about two hydrogen atoms and one oxygen atom for every carbon atom.

Question 2

D. fatty acid

C. protein

B. lipid

A. carbohydrate

In which type of molecule will you find peptide bonds?

Question 3

D. fatty acid

C. protein

B. lipid

A. carbohydrate

What biomolecule is represented in this diagram?

Question 4

D. lipid

C. protein

B. nucleotide

A. carbohydrate

Phosphate

SugarNitrogenous

base

Describe an enzyme and its function.

Question 5

Question 6Based on your knowledge of biomolecules, which of the following substances would be most effective at breaking down this polymer?

B. lipase

CH2OHO

OHHO

OH

OHOCH2

OH

HO

O

CH2OH

D. water

C. pepsin

A. nuclease

#1

The answer is D. A carbon atom has four electrons available for bonding in its outer energy level and needs to form four covalent bonds in order to become stable.

#2

The answer is A. Lipids are made mostly of carbon and hydrogen, and proteins contain nitrogen in addition to carbon, hydrogen and oxygen.

#3

The answer is C. Amino acids are the basic building blocks of proteins and are linked together by peptide bonds.

#4

The answer is B. Nucleotides are the smaller subunits that make up nucleic acids. Nucleotides are composed of three groups: a nitrogenous base, a simple sugar, and a phosphate group.

Phosphate

Sugar Nitrogenous base

#5

An enzyme is a protein that enables other molecules to undergo chemical changes to form new products. Enzymes increase the speed of reactions that would otherwise proceed too slowly. Substrate

Active site

#6

The answer is D. This is a sucrose molecule, formed from glucose and fructose in a condensation reaction. The products of this reaction are the sucrose molecule and water. If water is added to sucrose, hydrolysis occurs and breaks the covalent bonds between the subunits.

What to study for the test:

1. All of your notes and/or the PowerPoint slides on the blog

2. All worksheets we have done throughout this unit

3. Your vocabulary4. Your macromolecule foldable5. Look at your objective sheet and make sure

you know the things listed

1.Which four elements are the most common in living things? 2. What do you know about these four elements?

Documents

summary pages

electrons e

unit overview pages

natural elements

electron energy levelsatoms

equal numbers of electrons

trace elementstrace

electron cloud