Chemistry 201 Chapter 7

1869-1870: Mendeleev and Meyer

Independently stated that the elements can be
represented as periodic functions of their atomic
weights

Mosley (1913)

developed the concept of atomic
numbers

what are electrons attracted by?

nucleus

Do electrons repel each other?

true

effective nuclear charge (Zeef)

the net charge experiemced by an outer electron

what does “Z” stand for in Zeef= Z-S

the atomic number

what does “S” stand for in the Zeef= Z-S

the number of electrons between the nucleus and the outer electrons (screening constant)

are core electrons responsible for sheilding? (true or false)

true

in periodic trends, when does Z_eff stay the same?

When going from top to bottom within in a group in the periodic table.

in periodic trends, when does Z_eff steadily and significsnlty increase?

When moving from left to right across a period in the periodic table.

bonding atomic radius

one-half of the distance between covalently bonded nuclei

non-bonding atomic radius

refers to the closest separation of isolated atoms in close contact with each other

Bonding radius_?__non-bonding (< or >)

<

in periodic trends, when does the size or radius increase (due to value of n)

When going from top to bottom within in a group in the periodic table.

in periodic trends, when does the size or radius decrease (due to increase in Z_eff)

When moving from left to right across a period in the periodic table.

what does ionic size depend on?

charge on ion, number of electrons, the orbitals

cations (postitively charged ions) are _____than parent atoms

smaller

anions (negatively charged ions) are____than their parent atoms.

larger

when do ions increase in size?

within a group going from top to bottom and as the number of electron shells increases.

when does the size of an ion decrease?

with a period going from left to right

Iso-electronic ions

ions with the same number of electrons

Ionization energy

is the amount of energy
required to remove an electron from the ground
state of a gaseous atom or ion

The first ionization energy (I1)

is the energy
required to remove the first electron from a
neutral atom.

The second ionization energy (I2)

the energy
required to remove a second electron, from an ion
etc.

it requires____ energy to remove each
successive electron from an ion.

more

when does I_1 decrease?

within in a group goinf from top to bottom

why does I_1 decrease in periodic trend?

For atoms in the
same group, Zeff is
essentially the same,
but the valence
electrons are farther
away from the
nucleus

As you go from
left to right, Zeff
increases and
size decreases. I_1 ______(increases or decreases)

increases

Electron Affinity (EA)

the energy change
accompanying the addition of an electron to a
gaseous atom

In general, electron affinity becomes more
________ as you go from left to right
across a row (hint. energy)

exothermic

The noble gases have _____ electron affinities. (pos or neg)

positive

all metals tend to have_____ionization energies (lower/higher)

lower

metals tend to form___(cations/anions)

cations

nonmetals tend to have ___electron affinities. thus nonmetals tend to gain electrons to form anions. (high or low/ more or less)

high

metal oxide reacts with _____ to form a base

water

metal oxides react with _____ to form salt and water

acids

nonmetal oxides react with ____ to form an acid

water

nonmetal oxides react with ____ to form salt and water

bases

what metal produces bright colors when placed in a flame

alkali metal

allotropes

are different forms of the same compound in the same phase

____ removes electroms from any substance it comes into contact with

flourine

what is the most industrially useful element of halogens

chlorine

how many compounds does Xe form?

three

how many forms of Kr are stable

one