First Ionization Energy

• Definition from Topic 2 “Atomic structure”

First Ionization Energy

• Definition from Topic 2 “Atomic structure”– Minimum amount of energy required to remove

an electron from the atom to n = ∞in the gaseous state

Focus on the “First Ionization Energy” valuesComment on any trends/ patterns in relation to the atomic structure of an element

• Left to right: Across a period IE increases– On the left: Fewer valence electrons, in order to for cations, they

remove their electrons, therefore lower IE is expected– On the right: More full the shell is, they tend to gain electrons to

form anions, harder to lose electrons– Electrostatic attraction? Going from left to right, the number of

protons AND electrons increases, so does the electrostatic attraction• Nobel gases have the highest IE

– Already stable, do not tend to form ions anymore– Last shell completed, – Electrostatic attraction between protons (in nucleus) and electrons

• Up to down: More number of shells, IE decreases– (but after a point! After the transition metal, it stops)– the further distance away the valence electrons are from the

positively charged nucleus, weaker electrostatic attraction– Also, more full shells of electrons between the valence shell and the

nucleus, causing repulsion

• From top to bottom, the difference between the IE of each subsequent atom becomes smaller

• When the size of the atom increases down a group (top to bottom), the decrease in IE slows down– Energy levels converge at higher levels, ie they get

closer• Also, hydrogen is an exception– Lowest IE– Only has one single electron and proton,

electrostatic attraction is probably not that big

Watch

• Youtube: • Search for Khan Academy Ionization Energy

Effective nuclear charge (Zeff)

Effective nuclear charge (Zeff)• Zeff = [Atomic number of the element] – [Atomic number of the previous noble gas]

Ionization energy

• Last lesson you collectively explained the trends in ionization energy by applying prior knowledge and high intelligence

Divide into two groups

• Atomic radius and ionic radius– Nick– Chang– Fintan– August– Vera– Radina

• Electron affinity and electronegativity– Leo– Dominik– Michael– Klaudia– Isabel– Sarah

• Atomic radius and ionic radius– Nick– Chang– Fintan– August– Vera– Radina

• https://docs.google.com/a/isa.nl/presentation/d/1VXM2GxMFBDoa_D1kvPhMxOuvDSlwvlAn4tTwoGkd96w/edit#slide=id.p

Divide into two groups

• Electron affinity and electronegativity– Leo– Dominik– Michael– Klaudia– Isabel– Sarah

• https://docs.google.com/a/isa.nl/presentation/d/12UVIB1AJwuRlHc408H5U7tPoORByu9kaXcca8BYaOCc/edit#slide=id.p

Recap• Trends to discuss and explain in the periodic

table– Atomic radii– Ionic radii– Ionization energy– Electron affinity– Electronegativity

• Discuss across period (left to right) and down groups (top to bottom)

Periodic table

Atomic radii

Ionic radii

Ionization energy

Energy required to remove one mole of electrons from one mole of gaseous atoms in their ground state (kJ mol-1)

Why the discontinuities across a period?

• Draw the orbital diagrams of Z = 3 to Z = 10• Suggest explanation for the discontinuities based on electron

arrangements

Electron affinity

• Energy change when one mole of electrons is added to one mole of gaseous atoms (kJ mol-1)

• The opposite concept to ionization energy• Generally, energy is released as nucleus

attracts electrons– Exothermic, energy change is negative

• High the affinity = energy change more negative

Electronegativity

• The ability of an atom to attract electrons in a covalent bond

Explain electric conductivity using one of the periodic trends discussed

Reactivity of Group 1 Alkali metal

• Reaction with water– Demonstration: Sodium in water– Alkali metals: Explosive reactions• https://www.youtube.com/watch?v=QSZ-3wScePM

– Brainiac• https://www.youtube.com/watch?v=m55kgyApYrY

Why are they called “alkali metals”?

Balancing equation!

• Sodium + Water Sodium hydroxide + Hydrogen– Sodium hydroxide is alkali– Hydrogen is explosive

Periodic table

Other names

• Group 1: Alkali metals• Group 2: Alkaline earth metals• Group 17: Halogens• Group 18: Noble gases• Groups 3 to 12 (d-block): Transition metals• 4f elements: Lanthanoids• 5f elements: Actinoids