Unit 1 – Chemical Basis Unit 1 – Chemical Basis of Lifeof LifeImportant introductory terminology:Important introductory terminology:

biochemistry biochemistry - the chemistry of living thingsthe chemistry of living things

atomatom- the most basic particle of matter, consisting of a nucleus the most basic particle of matter, consisting of a nucleus

and electron(s) – e.g. hydrogen atomand electron(s) – e.g. hydrogen atom

elementelement- a substance made up of the same type of atom – e.g. gold a substance made up of the same type of atom – e.g. gold

moleculemolecule- a particle composed of two or more atoms (atoms can be of a particle composed of two or more atoms (atoms can be of

the same type or different type) – e.g. water molecule – Hthe same type or different type) – e.g. water molecule – H22O, O, nitrogen gas – Nnitrogen gas – N22

compoundcompound- substance made up of different type of atoms – e.g. carbon - substance made up of different type of atoms – e.g. carbon

dioxide – COdioxide – CO22

Chemical bondsChemical bonds- hold atoms together, some are hold atoms together, some are

stronger than othersstronger than others

3 main types of chemical bonds present 3 main types of chemical bonds present in living things – covalent, ionic and in living things – covalent, ionic and hydrogen bond:hydrogen bond:

1.1. covalent bondcovalent bond- strongest bond of three typesstrongest bond of three types- electrons are shared (e.g. Helectrons are shared (e.g. H22))

Covalent bond AnimationCovalent bond Animation

2.2. ionic bondionic bond- weaker bond than covalentweaker bond than covalent- electrons are not sharedelectrons are not shared- one atom takes one or more one atom takes one or more

electrons from another atom to electrons from another atom to create create ions (anionions (anion – a negative – a negative ion, ion, cationcation – a positive ion – a positive ion))

- change in charge of these atoms change in charge of these atoms (positive and negative charge) (positive and negative charge) creates an ionic attraction (e.g. creates an ionic attraction (e.g. NaCl – salt)NaCl – salt)

Ionic Bond animationIonic Bond animation

3.3. hydrogen bondhydrogen bond- weakest of the three bonds discussed (5% weakest of the three bonds discussed (5%

of the strength of a covalent bond), of the strength of a covalent bond), happens because of hydrogen’s poor happens because of hydrogen’s poor attraction to electronsattraction to electrons

- in water, the electrons collect more at the in water, the electrons collect more at the oxygen end of the molecule, giving this oxygen end of the molecule, giving this end a partial negative charge and the end a partial negative charge and the hydrogen end a partial positive charge.hydrogen end a partial positive charge.

- positive end of one water molecule has a positive end of one water molecule has a weak attraction to the negative end of weak attraction to the negative end of another water moleculeanother water molecule

- Give water it’s unique properties, such it’s Give water it’s unique properties, such it’s ability to stay a liquid at a wide range of ability to stay a liquid at a wide range of temperatures, and it’s high boiling point.temperatures, and it’s high boiling point.

hydrogen bonds

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hydrogen bonds also hold together hydrogen bonds also hold together the two rungs of the DNA ladderthe two rungs of the DNA ladder

hydrogen bonds

EntropyEntropy the natural progress from order to the natural progress from order to

disorder in living things (sometimes disorder in living things (sometimes thought of as randomness)thought of as randomness)

Constant supply of energy is needed Constant supply of energy is needed to combat entropy (in form of food for to combat entropy (in form of food for heterotrophic organisms, or sunlight heterotrophic organisms, or sunlight for autotrophic organisms)for autotrophic organisms)

Without a constant supply of energy, Without a constant supply of energy, living things die and become more living things die and become more randomrandom

This energy originates from the sunThis energy originates from the sun

chemical reaction-when chemicals react to create new substances

reactants- chemicals used up in a chemical reaction

products-chemicals produced in a chemical reaction

anabolism – building of more complex molecules using simpler molecules

catabolism – breaking down of more complex molecules into simpler ones

two types of chemical reactions exist: exothermic and endothermic

exothermic reaction- release energy into the surroundings when the chemicals react- 2 H2 + O2 2 H2O + energy (heat & light) – Hindenburg reaction

- C6H12O6 (glucose) + 6 O2 6 CO2 + 6 H2O +

energy (in the form of ATP, this famous exothermic reaction is called cellular respiration)

endothermic reaction- absorb energy from the surroundings when the chemicals react- e.g. - cold pack containing urea and ammonium chloride – mixed together causes reaction to absorb heat and the chemicals feel cold

- e.g. 6 CO2 + 6 H2O + energy (light) C6H12O6 (glucose) + 6 O2 this famous endothermic reaction is called photosynthesis)

Synthesis and Synthesis and Decomposition ReactionsDecomposition Reactions

Synthesis ReactionsSynthesis Reactions - is when there - is when there is a combination of two or more is a combination of two or more substances and a compound results substances and a compound results (also called (also called anabolismanabolism) . An example ) . An example of a synthesis reaction is as follows:of a synthesis reaction is as follows:

A + B --> ABA + B --> AB

a special type of synthesis reactions a special type of synthesis reactions occur in living systems, called occur in living systems, called dehydration synthesis dehydration synthesis (we will discuss (we will discuss later)later)

Decomposition ReactionsDecomposition Reactions is the is the opposite of synthesis. It is when a opposite of synthesis. It is when a compound is broken down into compound is broken down into simpler substances (sometimes simpler substances (sometimes called called catabolismcatabolism). An example of ). An example of decomposition is as follows:decomposition is as follows:

AB --> A + BAB --> A + B

a special type of decomposition a special type of decomposition reaction occur in living systems, reaction occur in living systems, called called hydrolysis (we will also hydrolysis (we will also discuss later)discuss later)

Chapter 2 - Question 1-3, Chapter 2 - Question 1-3, page 39page 391. What distinguishes one element from 1. What distinguishes one element from

another?another? The number of protons in the nucleusThe number of protons in the nucleus2. Describe the formation of an ionic 2. Describe the formation of an ionic

compound.compound. In sodium chloride, a sodium atom loses an In sodium chloride, a sodium atom loses an

electron to a chlorine atom.electron to a chlorine atom. The opposite charged ions are attracted to The opposite charged ions are attracted to

each other and form an ionic bond.each other and form an ionic bond.3. What is the difference between and ionic 3. What is the difference between and ionic

bond and a covalent bond?bond and a covalent bond? An ionic bond is formed due to the electrical An ionic bond is formed due to the electrical

attraction between oppositely charged ions.attraction between oppositely charged ions. A covalent bond is formed by atoms that A covalent bond is formed by atoms that

share electrons.share electrons.

Questions 4-6Questions 4-64. Compare and contrast – How does a molecule differ 4. Compare and contrast – How does a molecule differ

from an atom?from an atom? A molecule is made up of two or more atoms held A molecule is made up of two or more atoms held

together by a covalent bond.together by a covalent bond.5. Apply – Explain why a hydrogen atom can become 5. Apply – Explain why a hydrogen atom can become

either an ion or part of a molecule.either an ion or part of a molecule. A hydrogen atom has one unpaired electron in its A hydrogen atom has one unpaired electron in its

outer energy level.outer energy level. The electron can be lost to form an ion or shared to The electron can be lost to form an ion or shared to

form a covalent bond.form a covalent bond.6. Chemistry – A sodium atom has one outer electron, 6. Chemistry – A sodium atom has one outer electron,

and a carbon atom has four outer electrons. How and a carbon atom has four outer electrons. How might this difference be related to the types of might this difference be related to the types of compounds formed by atoms of these two elements?compounds formed by atoms of these two elements?

An atom that has a nearly full or nearly empty outer An atom that has a nearly full or nearly empty outer energy level (such as sodium) tends to form ions. An energy level (such as sodium) tends to form ions. An atom in between (such as carbon) tends to share atom in between (such as carbon) tends to share electrons.electrons.

Questions 1-3, page 43Questions 1-3, page 431.1. How do polar molecules form hydrogen How do polar molecules form hydrogen

bonds?bonds?- The oppositely charged regions of a polar The oppositely charged regions of a polar

molecule attract other polar molecules, allowing a molecule attract other polar molecules, allowing a positively charged hydrogen atom to bond to a positively charged hydrogen atom to bond to a negatively charged atom.negatively charged atom.

2.2. What determines whether a compound will What determines whether a compound will dissolve in water?dissolve in water?

- Compounds that have charges, such as ionic - Compounds that have charges, such as ionic compounds and polar molecules, will dissolve in compounds and polar molecules, will dissolve in waterwater

3.3. Make a chart that compares acids and bases.Make a chart that compares acids and bases.

- acids donate protons (hydrogen ions) and - acids donate protons (hydrogen ions) and bases accept thembases accept them

- acids have a pH less than 7, bases have a - acids have a pH less than 7, bases have a pH greater than 7pH greater than 7

Questions 4-5Questions 4-54.4. Compare and Contrast – How do polar Compare and Contrast – How do polar

molecules differ from non-polar molecules differ from non-polar molecules? How does this affect their molecules? How does this affect their interactions?interactions?

- Polar molecules have charged regions due to - Polar molecules have charged regions due to an unequal sharing of electrons. Non-polar an unequal sharing of electrons. Non-polar molecules do not have charged regions molecules do not have charged regions because electrons are shared more equally. because electrons are shared more equally. The charge differences tend to keep the The charge differences tend to keep the molecules separate.molecules separate.

5.5. Connect – Describe an example of Connect – Describe an example of cohesion or adhesion that you might cohesion or adhesion that you might observe during your daily life.observe during your daily life.

- Water beading on the surface, water sticking - Water beading on the surface, water sticking to the side of a glassto the side of a glass

Question 6Question 6

6.6. Cellular Respiration – When sugars are Cellular Respiration – When sugars are broken down to produce usable broken down to produce usable energy for cells, a large amount of energy for cells, a large amount of heat is released. Explain how the heat is released. Explain how the water inside the cell helps keep the water inside the cell helps keep the cell’s temperature constant.cell’s temperature constant.

- Water has a high specific heat.Water has a high specific heat.- Water in a cell can absorb a large amount Water in a cell can absorb a large amount

of energy before its temperature of energy before its temperature increases.increases.