Chapter 2 Biology Questions

What can happen to an electron when the sunlight hits it?

it can move out to a higher electron shell it can stay in its original shell

The compound CaSO4 ionizes into a calcium ion and a sulfate ion SO4. Calcium has two electrons in its outer shell. Upon ionization, what would you expect the charge on the sulfate ion to be?

-2

an electrically neutral molecule has the formula C3H4O2N. If the carbon atoms from the usual number of bonds, how many covalent bonds will each hydrogen atom have with other atoms in the molecule?

1

What coefficients must be placed in the following blanks so that all atoms are accounted for in the products?

2;2

An atoms atomic number is 7. its valence is most likely..

3

A particular carbon isotope has an atomic number of 6 and an atomic mass of 14. The respective number of neutrons, protons, and electrons that this carbon isotope has is ?

8, 6, and 6

The ammonia molecule in the diagram has the observed bond orientation b/c?

all of the above N has 4 pairs of electrons in the valence shell electrons repel one another N has 7 protons

Two C atoms from a double bond. Each C is bound to two H atoms. Which statement is true?

all the atoms lie in a plane

Ionic bonds form as a result of

attraction between ions that have opposite charges

What are radioactive isotopes useful in scientific research?

b/c they can be used as tracers to follow particular atoms and molecules through metabolic pathways

Covalent bonds hold atoms together because they...

fill shells without giving atoms much charge bring electrons closer to protons

compared with 31P, the radioactive isotope 32P has?

one more neutron

A covalent bond is likely to be polar if

one of the atoms sharing electrons is much more electronegative than the other

Ionization is?

the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions.

which of the following statements correctly describes any chemical reaction that has reached equilibrium?

the rates of the forward and reverse reactions are equal

Why do carbon atoms tend to make 4 covalent bonds?

the valence shell needs 8 electrons

Hydrogen bonding is most often seen ?

when hydrogen is covalently bonded to an electronegative atom

When do hydrogen bonds occur?

when partial opposite charges on molecules come close enough to attract each other

Given what you know about the human body, what do you think accounts for the high percentage of oxygen (65%)

The human body is made up pf mainly water, and there is one oxygen in every water molecule

When the proton number and electron number are unequal, the atom or molecule

is an ion

Which of the following subatomic particles has appreciable mass and lacks a charge?

neutron

a carbon atom and a hydrogen atom form what type of bond in a molecule?

nonpolar covalent bond

The chemical characteristics or reactivity of an element depend mostly on the

number of electrons in the outermost electron shell

In molecules C, H,O, and N atom usually make__,__,__, and _ bonds respectively

4, 1, 2, 3

we can represent atoms by listing the number of protons, neutrons, and electrons- for example, 2p+, 2n^0, 2e^- for helium. which of the following represents the 18^o isotope of oxygen?

8p+, 10n^0, 8e-

To fill the valence shell, an electrically neutral, unbonded atom with atomic number 8, must add...

2 electrons

The atomic number of sulfur is 16. Sulfur combines w/ hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.

H2S

the atomic number of sulfur is 16. Sulfur combines with hydrogen by covalent bonding to form a compound, hydrogen sulfide. Based on the number of valence electrons in a sulfur atom, predict the molecular formula of the compound.

H2S

Partial charges occur when..

a covalent bond links atoms of two kinds atoms share electrons unequally

In a double covalent bond, a carbon atom shares...

electrons in two orbitals

Without making or breaking bonds, the pictured molecule can change it's shape b/c?

rotation can occur around single bonds

By making two covalent bonds, an O atom( with 8 protons) fills its valence shell. Why does the atom's charge stay close to zero?

shared electrons aren't always close to oxygen oxygen keeps 6 electrons to itself. The 4 shared electrons migrate between O and the other atoms, thus contributing 4 half-charges to oxygen. This gives oxygen about 8 units of negative charge, balancing the atom's 8 protons.

which statement is true of all atoms that are anions

the atom has more electrons than protons

Copper has an atomic number of 29 and a mass number of 64. What would result if an uncharged copper atom lost two electrons?

the atomic number would remain 29, and the mass number would

In the term trace element, the adjective trace means that?

the element is required in very small amounts

the reactivity of an atom arises from

the existence of unpaired electrons in the valence shell