Ch 2B chem

An atom with 3 electrons in its outermost (valence) shell may have a total of ______ electrons altogether.

13

Based on the information in this figure, what is the atomic number of chlorine?

17 Prior to this reaction, the chlorine atom had 17 electrons. Therefore, chlorine must have 17 protons and an atomic number of 17

Atom

Smallest particle of an element that retains its properties.

What do these four elements have in common?

They all have an incomplete valence electron shell. The valence shell is the outermost electron energy level. Valence shell electrons determine the reactivity of an element.

A chemical bond is an energy relationship between outer electrons and neighboring atoms.

True

The reactivity of an atom is based on the number of electrons in its outer valance.

True Yes, you can predict whether an atom will become an ion or whether it will bond covalently based on the number of electrons in its outer valence.

How many hydrogen atoms will a single carbon atom bond with to form a stable molecule?

four Carbon has four electrons in its valence (outermost) electron shell. Therefore, it will form covalent bonds with four hydrogen atoms. The four electrons contributed by the hydrogen atoms will fill the valence shell of carbon.

Covalent bonds.

involve the sharing of one to three pairs of electrons. In single covalent bonds, one pair of electrons is shared; in double covalent bonds two pairs are shared; and triple covalent bonds involve sharing of three pairs of electrons. Double covalent bonds are common between carbon atoms in some organic molecules.

salts are always______.

ionic compounds

Lithium has an atomic number of 3. How many electrons are there in the outermost (valence) shell?

one

Hydrogen bonds are too weak to bind atoms together to form molecules, but they do hold different parts of a single large molecule in a specific three-dimensional shape.

true

What is an ion?

an atom that has either gained or lost electron(s) Ions form when atoms gain or lose electrons to attain a full valence shell, which gives them an electrical charge. Ions can be stored in the body, such as ions of calcium and phosphate that are stored in our bones, or can be available individually for many physiological processes. For example, Na+ is required for muscle contraction, nerve impulse conduction, and regulation of blood pressure.

What holds the sodium and chloride ions together in a chemical bond?

an electrical attraction between opposite charges The transfer of an electron results in ions with opposite charges that are electrically attracted to each other.

Which of the following is not produced through chemical bonding?

atoms Atoms react through chemical bonding to form larger structures. Chemical bonding begins with atoms; it does not produce them. All of the structures that we cover in A&P are made from atoms through chemical bonding.

A chemical reaction in which bonds are broken is usually associated with ________.

the release of energy

Calcium's atomic number is 20. It forms ions with 18 electrons. What is the electrical charge of a calcium ion?

+2 With atomic number 20, calcium atoms have 20 positive protons, and the ion has only 18 electrons, which means the net charge is +2. Calcium ions are essential for muscle contractions, nerve impulses, and bone maintenance.

How many valence shell electrons does the element carbon have?

4 Carbon has an atomic number of 6 and has four electrons in its outermost (valence) electron shell.

The numbers listed represent the number of electrons in the first, second, and third energy levels, respectively. On this basis, which of the following is an unstable or reactive atom?

2,8,1

Atom X has 17 protons. How many electrons are in its valence shell (outermost energy level)?

7

Ionic bond

A bond in which electrons are completely lost or gained by the atoms involved.

Nonpolar covalent bond

A bond in which electrons are shared equally.

Polar covalent bond

A bond in which electrons are shared unequally.

Hydrogen bond

A type of bond important in tying different parts of the same molecule together into a three-dimensional structure.

In a covalent bond.

Atoms share one or more pairs of electrons. In covalent bonds, atoms share ("co") their valence electrons ("valent"). These bonds are strong because to maintain stability the atoms must stay close enough together to continue sharing their electrons.

Examine the following reactions. Which of the following is true about compound C? Reaction 1 Reaction 2 Reaction 3 Reaction 4 A + B → C + D → E + F → G + H

C is the product of reaction 1 and a reactant for reaction 2. Excellent! In metabolic pathways, it is common for one reaction to produce something that then becomes a reactant for the next reaction.

Molecule

Combination of two or more atoms of the same element held together by chemical bonds

Cation

Electrically charged particle due to loss of an electron

sucrose

Excellent! Glucose and fructose are the reactants here. Sucrose is produced, and water is released in the process.

What type of bond is formed between the oxygen atom of one water molecule and the hydrogen atom of another water molecule?

Hydrogen bond The attraction between the slightly negative oxygen atom of one molecule and the slightly positively charged hydrogen atom within a separate water molecule is the basis of hydrogen bond formation. It is a form of dipole-dipole interaction.

Rank the chemical bonds from relatively weakest to strongest. I. Ionic II. Covalent III. Hydrogen

III < I < II Correct. Covalent bonds are the strongest because they involve sharing electrons. Ionic bonds are weaker and involve sharing charges. Hydrogen bonds are the weakest and involve sharing partial charges.

ionic compounds

Ionization, followed by ionic bonding An ionic bond is formed following the complete transfer of one or more electrons from one atom to another.

How do ions form ionic bonds?

Ions of opposite electrical charges are attracted to each other to balance the charges. Ions of opposite charges are drawn together to balance out their charges. Once they bond, they form an ionic compound that can store and transport the ions, or dissociate (separate), releasing the ions, which can then be used by the body.

Which of the following statements is false?

Larger particles move faster than smaller ones and thus collide more frequently and more forcefully.

Neutron

Neutral subatomic particle

Atoms of oxygen have a total of 8 electrons. Are the atoms stable, and why or why not?

No, because the atoms have only 6 valence electrons, but need 8 for stability. To be stable, by the Octet Rule an atom must have 8 electrons in its outermost orbital. With only 6 valence electrons, oxygen atoms are unstable and will seek ways to get or share two more electrons to become stable.

Which of the following distinguishes hydrogen bonds from covalent bonds?

Only hydrogen bonds can form between molecules

What explains the negative charge on the oxygen atom within the water molecule?

Oxygen atoms have a stronger pull on the electrons shared within a covalent bond formed between oxygen and hydrogen. Oxygen atoms are highly electronegative and pull electrons away from the electropositive hydrogen atom. Also, the nonbonding (lone) electron pairs on the oxygen, which are responsible for bending the molecule, are negative.

Which of the following is true of polar covalent bonds?

The electrons are shared unequally. Because the electrons are shared unequally, they spend more time around one atom than the other, causing a slight negative charge where they tend to hang out the most, and a slight positive charge where they spend the least time.

When an ionic bond forms, which part(s) of the atoms are directly involved?

The outermost electrons In ionic bonding, the atoms' outermost electrons—the valence electrons—are closest to each other and will interact, which leads to bond formation.

Which of the following is not a result of hydrogen bonds?

Two hydrogen atoms join together to form a molecule of hydrogen gas. Hydrogen bonds occur when there are polar covalent molecules present, but hydrogen atoms join with each other through nonpolar covalent bonds.

Which parts of atoms can interact (react) to form chemical bonds?

Valence electrons Only the outermost parts of atoms interact (react) with each other, and those are the valence electrons. If the outermost orbital is full, the atom is stable and less likely to react with another atom.

Carbon atoms have four valence electrons. Are they likely to react with other atoms, and why or why not?

Yes, because they can become more stable by doing so. Atoms react with other atoms to gain stability, typically by gaining, losing, or sharing electrons to attain a full outermost orbital. Atoms with full outermost electron orbitals are less likely to react and are referred to as being inert.

After the transfer of the electron, sodium will form an ion with __________.

a charge of +1 If sodium loses an electron, it will be positively charged. Although not shown explicitly in the figure, the element sodium contains 11 protons within its nucleus. If sodium forms a cation containing 10 electrons, it will have a charge of +1.

Which of the following correctly ranks the types of chemical bonds, in order, from strongest to weakest?

covalent, ionic, hydrogen In covalent bonds, electrons are shared between atoms; in ionic bonds electrons are lost or gained; but hydrogen bonds are not true chemical bonds—they are weak attractions due to slight electrical imbalances. No electrons are directly involved.

ATP → ADP + Pi is an example of a(n) ________ reaction.

decomposition

Bonds between carbon and hydrogen atoms (as depicted on the right side of the figure) are generally __________.

nonpolar covalent bonds Neither carbon nor hydrogen is considered an electronegative atom. Therefore, neither atom has an overly strong pull on shared electrons, and those electrons are shared equally within a nonpolar covalent bond.

Formation of hydrogen bonds requires hydrogen atoms and what else?

polar covalent bonds Hydrogen gets a slight positive charge from the unequal sharing of electrons in polar covalent bonds, and it bonds to another atom with a slightly negative charge, again resulting from unequal electron sharing due to a polar covalent bond.

A molecule of water (H2O) is formed by what type of bond?

polar covalent bonds The unequal electron distribution produces a slight negative charge on the oxygen and a slight positive charge on the hydrogens. These slight charges give water many unique characteristics that make it ideal for many physiological processes.

Amino acids joining together to make a peptide is a good example of a(n) ________ reaction.

synthesis

What is the most significant factor in the formation of a covalent bond?

the sharing of electron pairs between two atoms Covalent bonds are formed by the sharing of electrons between two reactive atoms.

One carbon atom can combine with two oxygen atoms to form carbon dioxide. Use the diagram to predict the type of bond that would be necessary to join the oxygens to the carbon to form a stable molecule.

two double bonds The formation of a double bond (the sharing of two electron pairs) between each oxygen and the carbon would result in each of the three atoms achieving a full valence shell.