You have mastered this topic when you can:

Transcription

1 BIO 12 U1TC CHEMISTRY REVIEW & INORGANIC LIFE MOLECULES 1 You have mastered this topic when you can: 1) describe and give examples matter 2) outline atomic structure 3) describe a chemical bond as an attraction between atoms 4) name, describe and explain the formation of ionic bonds, non-polar covalent bonds and polar covalent bonds 5) define and/or describe life molecules 6) identify these inorganic life molecules: acids, bases, buffers and water 7) describe and give examples of the properties of water that account for its importance to biological systems 8) distinguish between acids, bases and buffers and indicate the importance of ph to biological systems CHEMISTRY REVIEW [Section 21, pg 24] I) Everything you can touch, taste and or smell is an example of matter A) MATTER eg Hair, cloth, food, water, steel, chocolate and organisms 1) Matter is composed of millions of different compounds and molecules: eg water, glucose, amino acids, starch, cellulose, DNA, RNA, albumin, salt a) Compounds and molecules are composed of fixed combinations of about 92 naturally occurring elements B) ATOMIC STRUCTURE 1) Atoms are composed of varying combinations of 3 subatomic particles: protons, neutrons and electrons a) Protons and neutrons reside in the nucleus with electrons circling the nucleus in orbits [Fig 22: pg 25] b) Atoms This is accomplished by forming between atoms i) There are 2 types of chemical bonds that are formed between atoms: A} Ionic bonds The metal atoms give their outermost electrons, called valence electrons, to non-metal atoms creating positive metal ions and negative non-metal ions The opposite charges of these ions create a strong attraction causing the ions to bond to each other Compounds such as sodium chloride (NaCl), found in table salt, are formed this way [Fig 25: pg 27] 1} Ionic compounds All salts are ionic compounds R Ashby 2018 Duplication by permission only

2 BIO 12 U1TC CHEMISTRY REVIEW & INORGANIC LIFE MOLECULES 2 B} Covalent bonds [Fig 26: pg 28] 1} Non-polar covalent bond 2} Polar covalent bond a} The unequal sharing of electron pairs results in one end of the molecule being negatively charged while the other is positive the molecule is now POLAR eg water II) Required Practice 1: Pg 56: Complete Questions 1 & 2 {Answers are on page 523 of the text} INTRODUCING LIFE MOLECULES I) Life Molecules are the compounds and molecules necessary for an organism to survive A) There are 2 broad categories of life molecules: INORGANIC and ORGANIC R Ashby 2018 Duplication by permission only

3 BIO 12 U1TC CHEMISTRY REVIEW & INORGANIC LIFE MOLECULES 3 II) INORGANIC Life Molecules A) Inorganic life molecules B) WATER: The most important inorganic life molecule is water, H 2 O 1) The atoms in water are [Fig 27a: pg 28] 2) Water and have a Mickey Mouse shape [Fig 27a: pg 28] The polarity of water means it has different charges at its ends: the (δ ) while (δ + ) a) These opposite charges means water is sticky it attracts other water molecules and other charged or polar substances [diagram at bottom right of pg 29] i) The A} Although they are called bonds, hydrogen bonds are not chemical bonds in the same sense as an ionic or covalent bond A chemical bond involves electrons and forms between atoms 1} Ionic and covalent bonds involve electrons being transferred or shared between atoms 2} Hydrogen bonds involve an attraction between opposite charged ends of specific polar molecules Electrons are not part of a hydrogen bond 3} Ionic and covalent bonds are much stronger than hydrogen bonds B} There are several different forms of attraction between molecules hydrogen bonds are the strongest 3) Importance of Water a) Many organisms live in water based solutions: eg fish, whales, plants, some snakes, bacteria, protists b) Water makes up the greatest portion of many organisms total mass i) About 60% of an adult human s mass is due to water ii) About 95% of an jelly fish s mass is due to water iii) About 8% of a carrot s mass is due to water c) Chemical reactions of all organisms take place in water d) The polarity of water gives it life-sustaining properties [Ref: Properties of Water on pgs 29-30] Property of Water Function (role) 1 R Ashby 2018 Duplication by permission only

4 BIO 12 U1TC CHEMISTRY REVIEW & INORGANIC LIFE MOLECULES C) ACIDS: HCl(aq) H+(aq) + Cl (aq) D) BASES: NaOH(aq) Na+(aq) + OH (aq) R Ashby 2018 Duplication by permission only

5 BIO 12 U1TC CHEMISTRY REVIEW & INORGANIC LIFE MOLECULES 5 E) [H + ] (square brackets mean concentration of the substance inside them], dissolved in a solution [Fig 210: pg 31] 1) The ph of a solution is calculated using this formula: ph = log [H + ] a) i) ii) iii) 2) F) Buffers [Buffers and ph on pages 31 & 32] 1) Many life molecules, such as proteins, can only function correctly within a narrow ph range (remember: ph is a measure of the acidity of a solution) Buffers maintain a relatively constant ph by absorbing excess H + or OH 2) The carbonic acid bicarbonate ion buffer is extremely important blood based buffer in preventing acidosis (ph 70) or alkalosis (ph 78) by absorbing excess H + or excess OH a) The buffer is essentially this chemical equilibrium system: + i) as follows: + ii) as follows: + + 3) Read the section titled Buffers and ph on pages 31 & 32 of your text III) Required Practice 2: Pg 56: Complete Questions 3, 4, 5 & 6 {Answers are on page 524 of the text} R Ashby 2018 Duplication by permission only