Patterns within the periodic table: Completing the “Figure It Out” wkst should point out some very helpful trends that exist within the table … Be Careful, there are lots of deviations down here …

Do Now: Element 119 was just synthesized in a lab (not really). What would it’s electron configuration be and where would you place it on the periodic table?

Periodicity: (Periodic Trends) Certain atomic properties change predictably across, and up and down, the periodic table! Coulomb’s Law: Oppositely charged particles will be attracted to one another, similar charges will be repulsed. The force of the attraction (or repulsion) depends on the magnitude of the charges and the distance between them.

+1 -2 Which pair of particles will experience the stronger coulombic attraction? +3 -2

+2 -2 Which pair of particles will experience the stronger coulombic attraction? +2 -2

Periodicity: (Periodic Trends) Certain atomic properties change predictably across, and up and down, the periodic table! Coulomb’s Law: Oppositely charged particles will be attracted to one another, similar charges will be repulsed. The force of the attraction (or repulsion) depends on the magnitude of the charges and the distance between them. Greater charges = stronger attraction Greater distance = weakened attraction

Periodicity: (Periodic Trends) Certain atomic properties change predictably across, and up and down, the periodic table! Coulomb’s Law: Nuclear charge: (core charge) The nucleus is positive, the electrons are negative, they are attracted to one another. More protons in the nucleus = e- more strongly attracted (Coulomb’s Law)

Periodicity: (Periodic Trends) Certain atomic properties change predictably across, and up and down, the periodic table! Coulomb’s Law: Nuclear charge: (core charge) Shielding Effect: Outer electrons can be shielded from their attraction to the nucleus by other electrons. More inner electrons = more shielding for the outer e- = weaker attraction to nucleus

Periodicity: (Periodic Trends) Certain atomic properties change predictably across, and up and down, the periodic table! Coulomb’s Law: Nuclear charge: (core charge) Shielding Effect: Highest filled E level: Orbitals get bigger as the n value increases, so e-’s are further from nucleus, they are less attracted to it

SHIELDING -In a multielectron system, electrons are simultaneously attracted to the nucleus and repelled by each other. -Outer electrons are shielded from the nucleus by the core electrons. -The shielding causes the outer electrons to not experience the full strength of the nuclear charge. Certain atomic properties change predictably across, and up and down, the periodic table!

EFFECTIVE NUCLEAR CHARGE The effective nuclear charge is a net positive charge that is attracting a particular electron. Z is the nuclear charge, and S is the number of electrons in lower energy levels. Electrons in the same energy level contribute to screening but since their contribution is so small they are not part of the calculation. Trend is s > p > d > f. Zeffective = Z − S

Calculate the effective nuclear charge of Gallium Practice: Calculate the effective nuclear charge of Gallium Ga valence shell: 4s24p1 [Ar] core = 28- ; nucleus = 31+ 31 – 28 = +3 Zeff > 3+

Patterns in the Periodic Table Zeff increases as you move horizontally across the periodic table (same shielding, nuclear charge) Zeff slightly increases down a family because larger electron cores are less able to screen the outer electrons from the nuclear charge Not nearly as significant as across the row

‘THE ARESENAL’ Coulomb’s Law: Nuclear charge: (core charge) Shielding Effect: Highest filled E level:

PERIODICITY WATCH ME

Periodicity: (Periodic Trends) Atomic Size : Radius of an atom It’s all about how attracted the e-’s are to the nucleus! Stong attraction = smaller atom Weak attraction = larger atom

Model 1: Consider the “arsenal” components across the 2nd period Model 1: Consider the “arsenal” components across the 2nd period. Predict the trend! 3 p+ 4 p+ 5 p+ 10 p+

Explain WHY the trend exists across a period …

Model 2: Consider the “arsenal” components down the 1st column Model 2: Consider the “arsenal” components down the 1st column. Predict the trend! 1 p+ 3 p+ 11 p+

GENERAL TREND: (see below) Transition Metal Exception … Ten electrons is a lot to cram in one set of orbitals. Increased e- repulsions cause an increase in size.

GENERAL TREND: (see below) Transition Metal Exception … Ten electrons is a lot to cram in one set of orbitals. Increased e- repulsions cause an increase in size.

1. Which atom is predicted to be larger: sulfur or phosphorus 1. Which atom is predicted to be larger: sulfur or phosphorus? Explain your prediction.   2. Which atom is predicted to be larger: magnesium or strontium? Explain your prediction. 3. Place Cs, Rb and K in order of increasing atomic size. Draw a model as part of your answer that illustrates why the trend exists by showing important differences in the atomic structure of the atoms. 4. Place Al, C and Si in order of increasing atomic size. Draw a model as part of your answer that illustrates why the trend exists by showing important differences in the atomic structure of the atoms.