Ch 2 bio

Bases can ________.

both take up hydrogen ions and release hydroxide ions

The term to describe any substance which can prevent the pH of a solution from changing by either releasing or absorbing H+ in a solution is

buffer

An atom's outermost electron shell

determines its chemical reactivity

A covalent bond occurs when ________.

electrons are shared between two atoms to complete their octets

The type of bond that would form from the transfer of an electron from one atom to another, as depicted in the figure, is a. Two circles NA and CL

ionic

You are caring for the freshwater aquarium of a friend while they are on vacation. You are told to check the pH of the tank and make sure that it stays between 6.5 and 7.0. In order to assure that you do not have to worry about the pH you

add a buffer so changes in pH are minimized.

Which one of the following is the smallest unit of matter that has all the properties of an element?

atom

An atom that has an electrical charge is called a(n

ion

Which of the following is not one of the most common elements in living things?

iron

The pH scale is a mathematical indicator of

the concentration of H+ present in a solution

chemical bonds involve

the giving, taking or sharing of electrons.

The reactivity of an atom depends on

the number of valence electrons

A coke has a pH of 3.5. This means that it has an excess of _______ ions and would be called a(n) _____.

H+; acid

Which of the following is NOT a compound

O2

an ionic bond forms when

a negatively charged ion is attracted to one with a positive charge.

Isotopes of an atom differ in their

atomic mass

All atoms of the same element have the same

atomic number.

Inside a living cell, which type of bond would be the most stable

covalent

Some insects can stride on the surface of water because water

has surface tention

The atomic structure of water satisfies the octet rule by

having oxygen share electrons with two hydrogen atoms

The figure below is depicting the interaction of water molecules with one another which involves the use of ________.

hydrogen bonds

Which of the following explains the events occurring when water boils?

hydrogen bonds are broken between neighbor water molecules.

Isotopes of an element differ in their

neutron number

The particles that are found in the nucleus of an atom are the

neutrons and protons

Why do cells need buffering agents?

o minimize the changes in pH of their internal environment

A covalent bond involves the sharing of

pairs of electrons

In the reaction 6CO2 + 6H2O → C6H12O6 + 6O2 carbon dioxide is one of the _______.

reactants

Which of the following is a property of acids

release hydrogen ions when dissolved in a liquid

Which of the following is a property of acids?

release hydrogen ions when dissolved in a liquid

When hot chocolate mix is added to water the hot chocolate is the ______ and the water is the ________.

solute; solvent

Which of the following is not a way in which chemical bonds can be formed?

splitting electrons

The number of neutrons in the nucleus of an average atom of an element is best estimated by

subtracting the number of protons from the mass number.

Students were studying properties of water. One student placed a cup containing 80 mL of water in a freezer. Another student placed an identical cup containing 40 mL of water in the same freezer. Which of the following will be the same for both cups of water?

the temperature at which the water freezes

Which of these is a property of isotopes that make it useful in cell biology?

they behave the same chemically

Sulfur has an atomic number of 16. What would be the valence number of this element

two

A water molecule, as shown here, is polar because of ________.

unequal sharing of electrons

Which property of water would help to account for how an individual who is exercising and producing excessive heat can maintain a constant body temperature?

water has high heat capacity

What property of water causes sugar to dissolve in coffee

water is a good solvent

What is the steam being given off when water boils?

water molecules

Which of the following would not be a valuable use for radioactive isotopes

damaging DNA of healthy cells

Elements differ from each other in their ________.

physical properties and atomic number

After drinking a great deal of coffee (pH 5), a human's blood buffering system would need to ___ as the coffee was digested to lower the level of acid present in the blood stream.

take up H+

Which of the following describe how an acid disrupts the chemical bonds of molecules in a cell?

the H+ ions can disrupt hydrogen bonds as the slightly negative portion of the molecule is more attracted to it than to the hydrogen that was part of the bond.

You are caring for the freshwater aquarium of a friend while they are on vacation. You are told to check the pH of the tank and make sure that it stays between 6.5 and 7.0. When you check the water the pH is 8.0. The water in the tank is

10 to 15 times more basic than it should be.

The pH of pure water is ______ because ___________________________.

7.0; water dissociates an equal number of H+ ions and OH-

How do a strong acid and a weak acid differ? =

A weak acid dissociates only partially in water.

Which of the following is not a contributing event in the formation of acid rain

Fossil fuels consume oxygen removing it from the atmosphere.

Regarding atoms, identify which statement below is correct.

The number and arrangement of electrons in an atom governs its chemical activity.

Which of these does not occur when a sodium atom transfers an electron to a chlorine atom?

There is a sharing of the electrons between the sodium and chlorine atoms.

Radioactive isotopes are useful in biological studies because

an organism will take in a molecule with the isotope and use it normally but the radioactive decay can be detected.

Glucose, C6H12O6, is best described as a(n) ________.

compound

An element has an atomic number of 78. The number of protons and electrons in a neutral atom of the element are

78 protons and 78 electrons.

The electron arrangement for argon, which has 18 electrons, is

2 in the inner energy shell, 8 in the second energy shell and 8 in the outer energy shell

Which of the following is NOT a property of water?

It is denser when frozen than when liquid

Baking soda is sometimes used as an antacid. The chemical name for baking soda is Sodium Bicarbonate. What is the bicarbonate doing to help with stomach upset?

It is serving as a buffer to take up excess H+ ion from stomach acid.

Which of the following would be an example of the value of water's heat capacity

Living organisms are better able

If average temperatures from South Dakota were compared to temperatures from Oregon it would show that Oregon has warmer winters and cooler summers than South Dakota does. Account for why this could be when they are at similar latitudes?

The Pacific ocean makes Oregon temperatures more moderate.

Which of the following best describes the structure of how water molecules form and interact?

The oxygen atom and hydrogen atoms form a covalent bond with one another to create stable outer shells of electrons. The electrons are shared unequally resulting in a polar molecule whose slight charges form weak hydrogen bond attractions with other water molecules

What do lemons, tomatoes, and coffee all have in common chemically

They all produce (H+) in solution, making them acids

38. In what ways are radioactive isotopes potentially harmful?

Unmonitored release into the environment can make changes in a cell's DNA.

Of the following examples which best demonstrates the property of water cohesion?

Water can move up a 100 foot pine tree from the roots to the leaves.