chem

says that when the elements of the periodic table are arranged in order or increasing atomic number there are periodic patterns in their physical and chemical properties.

The Periodic Law

Period (series)

The horizontal rows of the Periodic Table

The elements in the periodic table are presently arranged in order of increasing

atomic number

Mendeleev organized the elements by...

increasing atomic mass AND so that elements in the same row have similar properties.

Henry Moseley rearranged the elements by...

increasing atomic number.

The d block elements are also known as the

transition metals

The elements in group do not have defined values for electronegativity.

18

Mg

2

O

2

Se

2

s

2

Al

3

N

3

P

3

Fluorine has the highest Electronegativity with a value of

4.0.

p

6

How would electronegativity change, going down a group?

Decrease

Rank these in the order of increasing atomic radii: Na, Rb, Li, K

Li < Na < K < Rb

Ions further down in a group (ex: Ba+2) have a larger radius than ions further up in the same group (ex: Mg+2). Why?

Lower group elements have more electron shells, further from the nucleus

The periodic table was first arranged by the scientist

Mendeleev

Which will have a higher atomic radius: Mg or P? Why?

Cl will have a higher atomic radius; it has another electron shell more than F and that is further from the nucleus.

The amount of energy required to remove the most loosely held electron from an atom is called the

(first) ionization energy.

Rank these in the order of increasing atomic radii: Si, Cl, Na, F

F < Cl < Si < Na

Cl

1

Cs

1

K

1

Li

1

Na

1

S

1

d

10

All the elements in group have an electron configuration that ends in p2.

14

f

14

Group Trend

As a general rule, electrons are harder to add as you move down a group.

As elements go across from left to right in a period, they hold their electrons more tightly, because they have more protons in the nucleus attracting the orbiting electrons in the electron cloud. So across a period, does atomic radius increase or decrease?

Atomic radii decrease from left to right across a period.

As elements go down a group, they have a whole additional energy level of electrons more than the element above them in the periodic table. Does atomic size increase or decrease down a group?

Atomic radii increase down a group

Atoms with fewer valence electrons tend to lose electrons while bonding in order to have a full outer shell. For each of the atoms below, write how many electrons the atom would lose to have a completed outer set.

Atoms with fewer valence electrons tend to lose electrons while bonding in order to have a full outer shell. For each of the atoms below, write how many electrons the atom would lose to have a completed outer set.

Atoms with lots of valence electrons tend to gain more electrons while bonding to fill their "octet" or "electron shell". For each of the atoms below, write how many electrons are needed to fill its shell.

Atoms with lots of valence electrons tend to gain more electrons while bonding to fill their "octet" or "electron shell". For each of the atoms below, write how many electrons are needed to fill its shell.

How are carbon and nitrogen different from each other when it comes to valence electrons?

Carbon has 4 valence electrons and nitrogen has 5

As elements go down a group from top to bottom, they don't get closer to filling up their outermost electron energy level, but that outermost electron level gets further away from the nucleus, so there is less attraction from the nucleus. Would it be harder or easier to remove an electron from an element further down in a group?

Easier to remove an electron as the number of shells increase

Electron affinity is a measurement of the energy released when an electron is added to a neutral atom.

Electron affinity is a measurement of the energy released when an electron is added to a neutral atom.

Would you expect a nonmetal atom (on the right side of the periodic table) to release energy when an electron is added to it or would energy be required for the electron to be added?

Energy would be released when an electron is added to a nonmetal. Nonmetals become more stable as they gain electrons, as they "try" to fill their electron shells or octets.

Would you expect a metal atom (on the left side of the periodic table) to release energy when an electron is added to it or would energy be required for the electron to be added?

Energy would be required. Metals become more stable when electrons are REMOVED from them, not when they gain more electrons.

For each of the elements below, write which block they can be found in.

For each of the elements below, write which block they can be found in.

For each of the type of subshell, write the maximum number of electrons that can fit in each subshell:

For each of the type of subshell, write the maximum number of electrons that can fit in each subshell:

Which will have a higher atomic radius: Ge or Br? Why?

Ge will have a higher atomic radius; it has fewer protons pulling on its outer electron shell

As elements go across from left to right in a period, they get closer and closer to filling up their outermost electron energy shell. Their protons hold tightly onto their electrons. As they get closer to filling up their outermost electron energy shell, would it be harder or easier to take an electron away from them?

Harder to take an electron away

Within nonmetals, ions that have additional electrons (ex: O-2) tend to be bigger than neutral atoms (ex: O). Why?

If there are more electrons, the attraction for each electron is a little bit less, as there are more electrons than protons in the nucleus.

Electronegativity is a measurement of how strongly an atom holds onto a pair of electron it already shares. How would you expect electronegativity to change from left to right on the periodic table?

Increase!

Ionization energy is the measurement of the energy needed to take away an electron from an atom. Explain how you think ionization energy would change in the periodic table and draw an arrow on the table below.

Ionization energy would be high if the atom is on the top right of the table and lower at the bottom left, as it is easier to remove an electron from further left and bottom atoms.

Within nonmetals, ions that have MORE additional electrons (ex: O-2) tend to be bigger than ions that have fewer additional electrons (ex: F-). Why?

More electrons means the attraction from the nucleus is "more spread out" and the electrons can spread out a little more than in ions that have fewer extra electrons.

Group (families)

The vertical columns on the Periodic Table

The element Vanadium (V) has an electron configuration of [Ar] 4s2 3d3Vanadium can exhibit several different oxidation states, but one of those is V+2. Given what you know about electron energy levels and electron configurations, which electrons would V lose to form V+2? Explain your answer below.

V loses the two s electrons first, because they are actually higher energy electrons (n=4).

How are valence electrons different from other electrons?

Valence electrons are the electrons in the outermost electron energy level or "shell".

Periodic Law

When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

Within metals, ions that have lost electrons (ex: Mg+2) tend to be smaller than neutral atoms (ex: Mg). Why?

When the ion has lost a whole level of electrons, the ion will definitely be smaller than the neutral atom. Plus, the nucleus is now attracting a smaller number of electrons. Each is pulled in more than before.

Within metals, ions that have lost MORE electrons (ex: Mg+2) tend to be smaller than ions that have lost fewer electrons (ex. Na+). Why?

With even fewer electrons, the electrons that remain are attracted even more by the nucleus that still has the same number of protons as the original atom.

Would you expect an atom further down in a group to have a higher electron affinity or a lower electron affinity than the atoms above it? Explain your answer.

You would expect the electron affinity to be slightly lower further down in a group, because the nucleus is further away from the electron being added. There is less energy needed to add another electron.

Ionization energy will increase as you move and decrease as you move

across the period; down the group.

Group 1 is also known as the metals.

alkali

Electronegativity is the ability of an atom to attract electrons to itself when the atom is in a

chemical bond.

Cd

d

Cn

d

Cr

d

Cu

d

The elements in group 12 have a electron configuration.

d^10

Electronegativity will as you move down a group.

decrease

As you move across a period from left to right, the size of an atom will . This is due to the increased number of that the atoms have as you move to the right.

decrease; protons

Period trend:

electron affinities become greater as you move from left to right across a period.

An atom with a positive or negative charge is called an ion. It becomes charged when it loses or gains

electrons.

The size of an atom is due mainly to the number of occupied that the atom has.

energy levels

Cf

f

Cm

f

The 2 rows on the bottom of the periodic table are also known as the

f block.

A vertical column on the periodic table is called a

group

Electronegativity will as you move across a period.

increase

As you move down a group, the size of the atoms will due to a greater number of as you move down the group.

increase; energy levels

The size of a negative ion is always than the size of the neutral atom from which it was made.

larger

The amount of energy required to remove a second or third electron from an atom is always than the amount of energy required to remove the first electron.

more

Ionic radii can change for a given ion. Use the internet to look up two things that can affect ionic radii and list them below.

oxidation state and coordination number

C

p

Cl

p

All the elements in group 17 will have a in their outermost energy level.

p^5

Ca

s

Cs

s

For Potassium (K), we would expect a large increase in ionization energy to occur when the electron is removed. This is because potassium will have the same electron configuration as before that electron is removed.

second (2nd); noble gas

The size of a positive ion is always than the size of the neutral atom from which it was made.

smaller