Trends in the Periodic Table

When atoms come together to connect, several factors are important, such as:

• WHAT

• WHAT

• WHAT

When atoms come together to connect, several factors are important, such as:

• Size

• Ease of losing electrons (how tightly their valence electrons are held together)

• Desire for gaining an electron or sharing an electron (depends on effective nuclear charge (Z*eff) and distance from the nucleus (shell #n))

Many properties of an atom depend on how tightly its WHAT are attracted to the WHAT, and the amount of WHAT charge that they feel

Many properties of an atom depend on how tightly its VALENCE ELECTRONS are attracted to the NUCLEUS, and the amount of POSITIVE charge that they feel

Usually, the WHAT electrons block the WHAT electrons from experiencing the full attraction of the nucleus. This is called “WHAT”

Usually, the CORE electrons block the VALENCE electrons from experiencing the full attraction of the nucleus. This is called “SHIELDING”

Example:

• The 2s electron of Li atom only feels the net charge of WHAT

Example:

• The 2s electron of Li atom only feels the net charge of +1

Effective nuclear charge (Z*eff) is the actual WHAT charge “felt” by an electron in an atom (other than hydrogen)

Effective nuclear charge (Z*eff) is the actual POSITIVE charge “felt” by an electron in an atom (other than hydrogen)

Z*eff = WHAT

Z*eff = Z - S

Z = Atomic number = nuclear charge

S = number of shielding core electrons

Electrons in the same shell do not WHAT each other

Electrons in the same shell do not SHIELD each other

Elements in the same group have similar WHAT

Elements in the same group have similar Z*eff

The distance of an electron from the nucleus is an important factor in the “WHAT” it feels (Z*eff) from the WHAT

The distance of an electron from the nucleus is an important factor in the “PULL” it feels (Z*eff) from the POSITIVE NUCLEUS

The distance of the valence electron from the nucleus increases by increasing the WHAT

The distance of the valence electron from the nucleus increases by increasing the n

Shielding and effective nuclear charge example

The electron cloud around nucleus has no WHAT so how do you measure the atomic radius

The electron cloud around the nucleus has no DEFINITE LIMIT/EDGE so how do you measure the atomic radius

Atomic radius is WHAT of the experimentally determined distance between two WHAT

Atomic radius is HALF of the experimentally determined distance between two IDENTICAL NEIGHBORING NUCLEI IN SOLID

Factors affecting the atomic size:

1. WHAT

2. WHAT

Factors affecting the atomic size:

1. Principal quantum number (n) for valence electrons

2. Effective nuclear charge felt by valence electrons

Going from top to bottom in a group

1. The principal quantum number (n) of the valence electrons WHAT

2. The effective nuclear charge for the valence electrons stays WHAT

Going from top to bottom in a group

1. The principal quantum number (n) of the valence electrons INCREASES

2. The effective nuclear charge for the valence electrons stays ALMOST STAYS THE SAME

The larger the n value, the larger are the WHAT taht contain the WHAT electrons

The larger the n value, the larger are the ORBITALS taht contain the VALENCE electrons

Atoms become larger by going from WHAT to WHAT in a group

Atoms become larger by going from TOP to BOTTOM in a group

Going from left to right across a period

1. Adds electrons to the same WHAT

2. The nuclear charge WHAT, while the number of core electrons stays the WHAT; effective nuclear charge for the valence electrons WHAT

Going from left to right across a period

1. Adds electrons to the same SHELL (n)

2. The nuclear charge INCREASES, while the number of core electrons stays the SAME; effective nuclear charge for the valence electrons INCREASES

Electrons are pulled closer to the WHAT as WHAT increases

Electrons are pulled closer to the NUCLEUS as Z*eff increases

Atoms become WHAT by going left to right in a period

Atoms become SMALLER by going left to right in a period

Ions are formed by adding or removing WHAT to/from the WHAT

Ions are formed by adding or removing ELECTRONS to/from the VALENCE SHELL

When sodium loses its valence electron, it still has HOW MANY protons and HOW MANY electrons left, so a positively charged particle is formed = WHAT

When sodium loses its valence electron, it still has 11 protons and 10 electrons left, so a positively charged particle is formed = CATION

Cations are always WHAT than original atoms

Cations are always SMALLER than original atoms

Number of protons are WHAT than the number of electrons in the cation, so the electrons are pulled WHAT to the nucleus → makes it smaller

Number of protons are MORE than the number of electrons in the cation, so the electrons are pulled CLOSER to the nucleus → makes it smaller

Going from top to bottom in a group, the size of cations with the same WHAT becomes WHAT, following the same trend as atom sizes

Going from top to bottom in a group, the size of cations with the same CHARGE becomes LARGER, following the same trend as atom sizes

Going from left to right in a period, the size of cations with different charges WHAT as the nuclear (+) charge WHAT

Going from left to right in a period, the size of cations with different charges DECREASES as the nuclear (+) charge INCREASES

Isoelectronic species have the same WHAT

Isoelectronic species have the same NUMBER of ELECTRONS

Sometimes a metal atom can lose more than one WHAT

Sometimes a metal atom can lose more than one ELECTRON

Transition metals always first lose electrons from the WHAT (ns), and then from the WHAT (n-1)d

Transition metals always first lose electrons from the OUTERMOST SHELL (ns), and then from the INNER SHELL (n-1)d

Less electrons for the same number of protons = WHAT

Less electrons for the same number of protons = STRONGER PULL for those electrons

WHAT tend to gain one or more electrons in WHAT shell to reach the electronic configuration of the noble gas next to them

NON-METALS tend to gain one or more electrons in VALENCE shell to reach the electronic configuration of the noble gas next to them

When chlorine atom gains an electron, there are 17 protons and WHAT electrons so a negatively charged particle forms a WHAT

When chlorine atom gains an electron, there are 17 protons and 18 electrons so a negatively charged particle forms a ANION

Anions are always WHAT than their parent atoms

Anions are always LARGER than their parent atoms

Number of protons are WHAT than number of electrons in the anion, so the electrons are WHAT pulled WHAT the nucleus. Also more WHAT between electrons

Number of protons are LESS than number of electrons in the anion, so the electrons are LESS pulled TOWARD the nucleus. Also more REPULSION between electrons

Going from top to bottom in a group, the size of anions with the same charge become WHAT

Going from top to bottom in a group, the size of anions with the same charge become LARGER

When atoms come together to connect, several factors are important

• WHAT

• WHAT

• WHAT

When atoms come together to connect, several factors are important

• Size

• Ease for losing an electron = Ionization energy

• Desire for gaining an electron or sharing an electron = Electron affinity

Ionization energy is the energy (kJ/mol) required to remove one WHAT from one WHAT

Ionization energy is the energy (kJ/mol) required to remove one (mole) ELECTRON(s) from one (mole) ISOLATED, GASEOUS atoms(s)/ion(s)

I.E (ionization energy) reflects how WHAT the electron is held by the WHAT in an atom

I.E (ionization energy) reflects how TIGHTLY the electron is held by the NUCLEUS in an atom

Sometimes I.E. is called “WHAT” = change in heat when removing an WHAT from an atom/ion

Sometimes I.E. is called “IONIZATION ENTHALPY” = change in heat when removing an ELECTRON from an atom/ion

I.E. is always WHAT (WHAT value)

I.E. is always ENDOTHERMIC (POSITIVE value)

First ionization energy (IE1) = energy to remove the most WHAT electron form a HWAT atom in WHAT state

First ionization energy (IE1) = energy to remove the most LOOSELY BOUND electron form a GASEOUS atom in GROUND state

First ionization energy

• Going from left to right across the period, IE1, WHAT as the atomic number (WHAT nuclear charge) WHAT

First ionization energy

• Going from left to right across the period, IE1, INCREASES as the atomic number (EFFECTIVE nuclear charge) INCREASES

First ionization energy

• Going from top to bottom in a group, IE1 WHAT as the period number (n) WHAT

First ionization energy

• Going from top to bottom in a group, IE1 DECREASES as the period number (n) INCREASES

First ionization energy

• Trends in IE are the WHAT of the trends in atomic size

First ionization energy

• Trends in IE are the OPPOSITE of the trends in atomic size

First ionization energy

• Non-metals have WHAT IE1, while metals have WHAT IE1

First ionization energy

• Non-metals have LARGEST IE1, while metals have SMALLEST IE1

Larger the atom = WHAT the IE1

Larger the atom = SMALLER the IE1

Successive ionizations are possible until no WHAT remains

Successive ionizations are possible until no ELECTRON remains

Successive ionization energies require more WHAT to remove an electron form a WHAt ion

Successive ionization energies require more ENERGY to remove an electron form a POSITIVE ion

It requires much more energy to remove the WHAT electrons

It requires much more energy to remove the CORE electrons

Some atoms have an “WHAT” or “WHAT” for electrons

Some atoms have an “AFFINITY” or “LIKING” for electrons

Electron affinity (E.A.) is the desire that a WHAT atom/ion has for adding an electron to its WHAT

Electron affinity (E.A.) is the desire that a GASEOUS atom/ion has for adding an electron to its VALENCE SHELL

Electron affinity is measured by the WHAT or WHAT (∆H in kJ/mol) that is absorbed or released when one (mole) electrons is added to one (mole) isolated, gaseous atom(s)/ion(s)

Electron affinity is measured by the HEAT or ENTHALPY (∆H in kJ/mol) that is absorbed or released when one (mole) electrons is added to one (mole) isolated, gaseous atom(s)/ion(s)

For almost all elements ∆(EA)H < 0 (WHAT, WHAT E.A.) but it can also be ∆(EA)H > 0 (WHAT, no WHAT)

For almost all elements ∆(EA)H < 0 (EXOTHERMIC, HIGH E.A.) but it can also be ∆(EA)H > 0 (ENDOTHERMIC, no DESIRE)

Going from left to right across a period, E.A. WHAT as the atomic number (effective nuclear charge) WHAT

Going from left to right across a period, E.A. INCREASES as the atomic number (effective nuclear charge) INCREASES

The more WHAT ∆(EA)H the WHAT the tendency of an atom to WHAT the electron

The more NEGATIVE ∆(EA)H the GREATER the tendency of an atom to ACCEPT the electron

WHAT have higher “affinity” for the electron ( more HWAT) forming, WHAT don’t like to form anions

NON-METALS have higher “affinity” for the electron ( more NEGATIVE ∆(EA)H) forming (eg, O-, S-, F- and Cl-), METALS don’t like to form anions

Addition of electrons to an WHAT with negative charge requires WHAT (∆(EA)H WHAT 0)

Addition of electrons to an ANION with negative charge requires ENERGY (∆(EA)H > 0)

Atomic size on the periodic table for larger

Ionization energy on the periodic table for larger

Electron affinity on the periodic table for larger