Chapter 2

An article in a medical journal indicates that researchers have used an isotope 3H to trace to a certain metabolic process. From the symbol that is given, we know this is a hydrogen isotope with

1 proton and 2 neutrons (Hydrogen normally has 1 proton and NO neutrons. Proton number never changes which means that a hydrogen atom with an atomic mass of 3, must have 1 proton and 2 neutrons) SEC: 02.01

A solution with a pH of 7.0 has _______ times _______ H+ than a solution of pH 10.

1,000; more Sec: 02.04

The periodic table gives you the following information about oxygen: -8 -0 -15.99 A scientific article that you are reading mentions oxygen-18. How is oxygen-18 different from the typical oxygen atom described in the periodic table? Select all that apply.

1. Oxygen-18 is an isotope 2. Oxygen-18 has 2 additional neutrons (Oxygen-18 is an isotope of oxygen. Isotopes differ in their number of NEUTRONS. A typical oxygen has an atomic mass of 16 (8 protons + 8 neutrons), oxygen 18 would still have 8 protons (proton number does not change) but it would have 10 neutrons). Sec: 02.01

The periodic table displays the following information about the element phosphorus? Select all that apply. -15 -P -30.794

1. Phosphorus has 15 protons 2. Phosphorus will form chemical bonds with other elements. (The atomic # of phosphorus is 15. Meaning it has 15 protons (+) and therefore 15 electrons (-). The first two electron shells would be full but its VALENCE shell would be incomplete without 5 out of 8 electrons and therefore it will form chemical bonds with other elements. | Sec: 02.01)

A solution with a pH of 6 has _______ times _______ OH- than a solution of pH 10.

10,000; less Sec: 02.04

Prior to prescription medications to control stomach acid and "heart burn" people consumed baking soda (sodium bicarbonate) to decrease their discomfort. This would indicate that sodium bicarbonate

neutralizes stomach acid by combining with excess H+ (Sodium bicarbonate neutralizes stomach acid by combining with excess H+) Sec: 02.04

An atom's mass is best described as the mass of

protons and neutrons it contains (protons + neutrons= atomic mass) sec: 02.01

Human blood has a pH of about 7.4. This is

slightly basic Sec: 02.04

A valence shell is best described as

the outermost electron shell of an atom sec: 02.01

Which type of covalent bond is the strongest?

triple covalent bond Sec: 02.02

How many atoms are required to form a molecule?

At least 2 Sec: 02.02

If the atomic number of chlorine is 17 and the atomic mass is 35, how many neutrons are there in the nucleus?

18 (The number of protons = the atomic number; atomic mass is protons + neutrons. If the atomic mass is 35 then 17 + N = 35. There are 18 neutrons.) | Sec: 02.01

What is the maximum number of electrons that will be in the first valence shell?

2 Sec: 02.01

If an element contains 8 electrons how many electrons will be placed in the 2nd valence shell?

6 -- 2 in first valence shell and remaining 6 in second. Sec: 02.01

This system of chemicals,H2CO3↔ H+HCO3 , act as a buffer in the blood. If hydrogen ions are added to blood which of the following reactions would occur? A. H+ + HCOᵥ3 →Hᵥ2COᵥ3 B. OH + Hᵥ2COᵥ3 → HCOᵥ3- + Hᵥ2O

A. H+ + HCOᵥ3 →Hᵥ2COᵥ3 (If hydrogen ions are added to blood, bicarbonate ions would combine with the acid forming carbonic acid). Sec: 02.04

Which property of water allows it to stick to surfaces like glass?

Adhesion (Because water molecules have charges, they like to stick to other things with charges such as glass. Adhesion describes the attraction of water molecules to others charged substances, WHERE AS cohesion is attraction to itself - water to water). Sec: 02.03

What does the graph reveal about the heat of vaporization and the heat fusion?

After studying the graph, ones sees that it takes over 500 calories of heat to convert one gm of the hottest liquid water to a gas. To convert one gm of the coldest liquid water to a solid quirres the loss of about 80 calories.

Which statement is not true about subatomic particles? -Protons are found in the nucleus -Neutrons have no electrical charge -Electrons contain much less mass than neutrons -Electrons are found in orbitals around the nucleus -All electrons in an atom contain the same amount of energy

All electrons in an atom contain the same amount of energy Sec: 02.01

In a water molecule.. -the oxygen atom is more electronegative than the hydrogen atoms -the oxygen atom has an overall negative charges with the hydrogen atoms having an overall positive charge -unequal sharing of electrons results in a polar molecule -All of the choices are correct

All of the choices are correct Sec: 02.02

As a solid, water floats. This means that... A. solid water is less dense than liquid water. B. organisms in ponds, lakes, and reservoirs can survive under the ice cover. C. this is due to hydrogen bonding changes. D. All of the choices are correct.

All of the choices are correct. Sec: 02.03

Which statement is NOT true about ionic bonds?

An ion has the SAME number of electrons as a nonionic atom of the same element. (In order for an atom to become an ion, it must either gain or lose one of more electrons) sec: 02.02

Your roommate has heartburn and you hand her a bottle of antacids. She wants you to explain how the antacids will make her feel better. What do you tell her?

Antacids are BASES and can TAKE UP H+, thereby REDUCING the acidity of the solution. (Antacids are bases and by definition can ABSORB H+ out of a solution). | Sec: 02.04

Following nitrogen (78%) any oxygen (21%), argon is the next most common gas in the atmosphere (less than 1%). Checking the table of elements, you discover that argon is one of the family of atoms with outer shells already full of electrons. How is this related to the fact that these atoms have virtually no biological importance?

Argon has an outer shell with 8 electrons. These atoms are stable, ordinarily not reacting with other atoms. Therefore, argon only exists as a pure substance which has no biological importance. Sec: 02.01

Which of the following statements is NOT true about electrons configurations?

Atoms with more than 8 electrons in the outer shell REACT by GAINING electrons. (8 electrons on an outer valence shell would not need any more electrons) Sec: 02.01

If you place the corner of a paper towel into a droplet of water the water moves across the paper towel. Which of the following would explain the movement of the water?

BOTH cohesion and adhesion. (Cohesion is holding the water molecules together within the droplet. The water molecules are attracted to the paper which is adhesion). | Sec: 02.03

Which substances are on the basic side of the pH Scale?

Baking soda, oven cleaner, and human blood Sec: 02.04

Which of the following elements would be the most reactive with other elements?

Boron #5 | Sec: 02.01

Which of the following substances attract water molecules? -A nonpolar substance -A polar substance -An ionic substance -Both polar and ionic substance -All of the above will attract water molecules

Both polar and ionic substance (Since water is a polar (+) molecule is has charges , it is attracted to other substances with charges. Nonpolar substances do not have charges and therefore do not attract water). Sec: 02.03

Which terms refers to the attraction of water molecules to one another?

Cohesion (It is the attraction of a water molecule to another water molecule. Ex: A water droplet) Sec: 02.03

Which statement is NOT true about covalent bonds?

Covalent bonds form when an electron is completely lost or gained from an atom. (Ionic bonds form when atoms gain or lose electrons. COVALENT bonds form when atoms SHARE one of more pairs of electrons). Sec: 02.02

From the table below, it is apparent that: BOND ENERGY(kcal/mol) C-C 83 C=C 146 C-O 84 C=O 170

Double bonds are stronger than single bonds Sec: 02.02

What relationship can be determined by the following information? -The radioactive isotope iodine 131 has a half-life of 8.1 days and emits 0.8 MeV (millielectronvolts) of energy. -The radioactive isotope phosphorus 32 has a half-life of 14.3 days and emits 1.7 MeV (millielectronvolts) of energy. -The radioactive isotope phosphorus 33 has a half-life of 25.5 days and emits 0.25 MeV (millielectronvolts) of energy. -The radioactive isotope sulfur 35 has a half-life of 87.5 days and emits 0.2 MeV (millielectronvolts) of energy.

Energy and half-life are not directly related Sec: 02.01

Which of the following is TRUE about about the PH Scale? *The scale ranges from 1 to 15

FALSE Ranges from 1-14. Sec: 02.04

The electrons are unequally shared in ______, and transferred in _________.

H2O, Na+Cl- SEC:02.02

A COASTAL climate is moderated primarily by which of the following properties of water?

Has a high head of evaporation Sec: 02.03

Which are NOT true about the electrical charges of elements? -Protons carry a positive charge -In an atom, the number of protons and neutrons MUST be equal -An atom is neutral when the positive and negative charges balance -Neutrons have no electrical charge

In an atom, the number of protons and neutrons MUST be equal Sec: 02.01

The characteristics way in which atoms of an element react is most related to the

Number of ELECTRONS in the VALENCE shell. Sec: 02.01

Both 18O and 16O are found in nature. However, 16O is the most common. Therefore,

Oxygen atoms can have 8-10 neutrons sec:02.01

The mass number refers to the number of _______ and ______ within the element.

Protons; neutrons Protons + Neutrons = Mass number Sec: 02.01

Draw the structural formula of a single water molecule. Note the location of the partial positive and negative charges. Label the covalent bonds.

See page 16 of your study guide? :) lol

Draw 2 water molecules and the hydrogen bonding that may occur between molecules. Define hydrogen bonding and explain how and why it occurs.

See page 17 of your study guide ;)

Draw several (5 or 6) individual, unbonded water molecules. Simulate what happens when table salt (Na+C1-) is added to water. Use the model you created to explain why salt is added to the roads in a "snowy", cold climate.

See page 18 of your study guide ;)

Study the chart to determine the relationship between H+ concentration and pH. If you were to create a herbal remedy to decrease excess stomach acid, would you create a solution with a relatively greater or lesser number of hydrogen ions?

See page 19 for chart :) To neutralize excess stomach acid, one would create an herbal medication with lower concentrations of H+. Solutions with lower concentrations of H+ would have relatively higher pHs. Sec: 02.04

Use Bohr's model to draw a sodium (Na) atom and a chlorine (C1) atom. Using your model, explain what happens when sodium reacts with chlorine to form table salt. Include your explanation ion and ionic bond formation.

See page 21 for model Sec: 02.02

Which of the following is TRUE about about the PH Scale? *The scale indicates the relative concentration of hydrogen and hydroxide in ions in a solution

TRUE SEC: 02.04

Which of the following is TRUE about about the PH Scale? *A change of one pH unit represents a 10-fold increase or decrease in hydroxide ion

TRUE Sec: 02.04

Which of the following is TRUE about about the PH Scale? *Any substance below pH7 is considered acidic and any substances above pH7 is considered basic or alkaline

TRUE Sec: 02.04

Which of the following is TRUE about about the PH Scale? *pH 7 has a balanced level of H+ and OH-

TRUE Sec: 02.04

To determine the age of fairly recent fossils and organic artifacts, it is possible to analyze the amounts of isotopes 14C and 14N, because overtime the 14C- which originated in the atmosphere-breaks down into 14N through a process known as BETA DECAY. What net change occurred for this to happen?

The 14C GAINED a PROTON Sec: 02.01

Which one is NOT one of the properties of water? -The frozen form is MORE dense than the liquid form -Water moderates temperature -Water is a solvent -Water has a high heat capacity -Water has a high head of evaporation

The frozen form is actually LESS, not more dense than the liquid form Sec: 02.03

Draw two hydrogen atoms using Bohr's model. Now bond them to form a molecule of hydrogen gas. Write the molecular formula. Explain what type of bond you've created and why this is a stable situation.

The molecular formula is H2. A Nonpolar covalent bond is created when 2 of the SAME element EQUALLY SHARE a pair of electrons. Through sharing, both atoms now have a completed outer shell with two electrons. This is a stable molecule. See page 22 for drawing. SEC: 02.02

Which statement is not TRUE about polar covalent bonds?

The oxygen of a water molecule is electropositive relative to the hydrogen (The oxygen of a water molecule is electroNEGATIVE (-) relative to the hydrogen (+) sec: 02.02

The blood buffer reactions described by H2CO3 <-----------> H+ + HCO3- indicates that

The reaction can flow either direction depending on whether there is too much H+ too much H+ is needed. Sec: 02.04

All of the following are examples of damage caused by acid deposition from rain EXCEPT

increased agricultural yields Sec: 02.04