Ch.2 Flashcards
Atoms contain three types of particles, positively charge
- Protons
- Electrons
- Neutrons
Within an atom’s structure, electrons can be found in cloud like
orbitals
Select all of the following that are true about atoms that have partially filled energy shells.
- They can form compounds.
- They tend to share, lose, or gain electrons.
An atom’s atomic number is based on the number of
protons
Oxygen has eight protons, eight electrons, and eight neutrons. What is its atomic mass?
16
True or false: Electrons are found in the atom’s nucleus.
False
A mole of a certain substance has a number of particles equal to
12 g of carbon
An electron shell is composed of one or more
orbitals
Why is the atomic mass of carbon reported in the periodic table slightly greater than its predicted mass?
Because of the presence of a small amount of heavier isotopes
valence ______electrons enable chemical bonds to form among atoms.
Unpaired
An atom’s atomic number represents
the number of protons.
By mass, the most abundant element in living organisms is
oxygen
The chemical formula of glucose is C6H12O6. How many oxygen atoms are in one molecule of glucose?
- 6
The atomic mass numbers reported in the periodic table do not exactly match calculations based on protons and neutrons due to
the presence of different isotopes of the same element.
covalent bond is one in which a pair of electrons
is shared between two atoms.
What four elements are the most common in living organisms?
- Hydrogen
- Oxygen
- Carbon
- Nitrogen
Why are atoms likely to share electrons?
Because they have unfilled outer electron shells.
A new element found on earth has four unpaired electrons in its outer shell. Predict the maximum number of bonds in which the new element can participate.
4
A covalent bond in which the atoms share electrons unequally is a(n)
polar covalent bond
Atoms share a pair of electrons when they form a(n)
covalent bond
Which of the following statements are true of a polar covalent bond?
- The two atoms in the bond share the electrons unequally.
- The atoms in the bond differ in electronegativity.
Which of the following covalent bonds are polar?
- O-H
- N-H
According to the _______ rule, atoms tend to be most stable when their outer shells are filled; this can be accomplished by gaining, losing, or sharing ________.
- Octet,
- electrons
The bond between the hydrogen atom and oxygen atom of separate water molecules is a(n)
Hydrogen Bond
Nitrogen has three unpaired electrons in its outer shell. The maximum number of covalent bonds that a nitrogen atom can form with other atoms while still remaining uncharged is
3
Van der Waals forces arise when
random electron movement creates short-lived attractions.
In a polar covalent bond, the shared electrons are closer to the nucleus of the atom with
greater electronegativity.
A Na+ion forms when
a sodium atom loses an electron.
A(n) ______ bond is formed when two atoms of different electronegativities share electrons.
polar covalent
Which of the following covalent bonds are nonpolar?
- O-O
- H-H
An ionic bond forms when a positively charged ion, called a(n) _____, interacts with a negatively charged ion, called a(n) ____
- cation
- anion
Van der Waals interactions can form between
any atoms
Which of the following properties are shared by many chemical reactions that occur in cells?
- They often require a catalyst.
- They tend to proceed toward equilibrium.
- They require energy.
What type of bond forms when a cation with a positive charge interacts with an anion carrying a negative charge?
Ionic
Ionic Bond
- Bond between a cation and an anion
Hydrogen Bond
- bond between atoms and partial positive and partial negative charge
Polar covalent bond
Bond in which two atoms share electrons unequally
Non-polar covalent bond
Bond in which two atoms share electrons equally
Chemical reactions require a source of energy and also may require a substance called a(n)_____ that speeds up the reaction rate. Most chemical reactions proceed toward a state called, _____ in which the rate of product formation equals the rate of reaction forms
- enzyme
- equilibrium
Which of the following statements describe hydrophilic molecules?
They are soluble in water.
A(n) ______ bond is formed when two atoms of different electron-negativities share electrons.
polar covalent
Amphipathic molecules have both
- hydrophobic and hydrophilic
The amount of solute (in grams) dissolved in a given volume of solution is the solution
concentration
Which types of chemical bonds are easily broken in water?
- Ionic bonds
- Hydrogen bonds
The atomic mass of hydrogen is 1, and the atomic mass of oxygen is 16. What is the molecular mass of a water molecule (H2O)?
18
When water freezes
- water molecules are packed into a more orderly formation.
- the rate of hydrogen bond breakage slows.
Select all of the following that describe hydrophobic molecules.
- They are relatively insoluble in water
- They contain many nonpolar covalent bonds.
An amphipathic molecule
- has polar regions.
- has non-polar regions.
Water has a high heat of fusion. This means that
- much energy must be withdrawn to cause water to change from a liquid state to solid.
The concentration of a liquid is defined as the amount of ______ dissolved in a unit volume of solution.
- solute
The atomic mass of carbon is 12, and the atomic mass of hydrogen is 1. What is the molecular mass of a methane molecule (CH4)?
16
Polar covalent O-H bonds in water molecules enable hydrogen bonds to form between water molecules. Which of the following properties of water result from hydrogen bond formation?
Cohesion Adhesion Surface tension High specific heat High heat of vaporization
Which of the following contributes to water’s stability in a liquid state?
- A high heat of fusion
- A high heat of vaporization
Pure water can ionize into
- positively charged protons (H+) and negatively charged hydroxide (OH-) ions.
High specific heat, surface tension, and cohesion are several properties of water involving
hydrogen bonds
Sodium hydroxide is a base because when dissolved in water it binds _________ ions that are in solution.
hydrogen
The pH of a solution is defined as the ______ (base 10) of the hydrogen ion concentration
negative logarithm
Acidic
Contains more H+ than OH- ions
Alkaline:
Contains more OH- than H+ ions
Neutral:
Contains equal numbers of OH- and H+ ions
Living organisms minimize changes in their internal pH using compounds called
buffers
When water ionizes, it produces what ions? Select all that apply.
- OH–
- H+
Which substance is acidic?
stomach fluid
The ______ of a solution is the negative base 10 logarithm of the H+concentration of the solution.
pH
Arrange the following solutions in order ofincreasingproton concentration. The solution with the lowest proton concentration should be placed at the top of the list.
- alkaline
- Neutral
- Acidic
What type(s) of compound(s) minimize pH fluctuations in the fluids of living organisms?
- buffer
- buffering agent
Living organisms minimize changes in their internal pH using compounds called
buffers