Periodic Properties of Elements Tadas Rimkus Krishna Trehan Rachel Won Soo Jeon

What is the SWBAT???? Objective Know a brief history of the periodic table Know the effective nuclear charge Examine periodic tends in the atomic size, ionization energy, and electron affinity Examine the sizes of ions and their electron configurations Explore some of the difference in the physical and chemical properties of metals, nonmetals, and metalloids. Discuss some periodic trends.

I <3 The Periodic Table Mendeleev, Meyer, Moseley strived to investigate the possibilities of classifying elements in useful ways. Mendeleev and Meyer - developed the periodic table on the basis of the similarity in chemical and physical properties. He predicted Ga, Ge, and Sc. Moseley- established that each element has a unique atom number. - found out that each element produces X rays of a unique frequency; the frequency increases as the atomic mass increases Rutherford- proposed the nuclear model of the atom. Element in the same column of the periodic table have the same number of electrons

Sizes of Atoms and Ions Ionic size - the size of an ion plays an important role in determining the structure and stability of ionic solids! Periodic Trend - Metals tend to lose electrons. The size of the atom becomes smaller with the loss of each!

Continue… Consecutive electron. The nuclear charge can have a greater pull on the electrons with the loss of each electron. Iso-electronic ions - ions containing the same number of electrons, thus having the same electron configuration!

Continue… AGAIN! Periodic Trend - Nonmetals tend to gain electrons. The size of the atom becomes larger with the addition of each consecutive electron. The nuclear charge has less of a pull on the electrons with the gain of each electron due to greater electron repulsion!

7.5 Electron Affinities Ionization Energy: energy required to remove an valence electron Cl(g)  Cl+(g) + e- ΔE = 1251 kJ/mol See how E is positive? This is the energy which you must add, in order to remove an electron from Chlorine

Electron Affinity Did you know that atoms can gain electrons to gain a negative charge?! This energy change that occurs is called ELECTRON AFFINITY because it measures the ATTRACTION between the newly added electron and the atom It shows how much the atom WANTS the electron!

Electron Affinity So……. FLUORINE wants an electron MORE than LITHIIUM, meaning it would have a LARGER electron affinity! http://www.chemguide.co.uk/inorganic/group7/eadiag.gif

Ionization Energy the amount of energy need to remove an electron from a specific atom or ion in its ground state 1st Ionization Energy energy needed to remove the 1st electron from an atom

Ionization Energy… CONTINUE ACROSS- increase As you go across the periodic table, the electrons are closer to the nucleus increasing the energy necessary to remove an electron DOWN- decrease As you go down the periodic table, the electrons are farther from the nucleus

Continue! Nuclear Charge the change in the nucleus or the number of protons ACROSS- increase DOWN- increase Atomic Radius one half the distance from center to center of like atom down-increases As you go down the periodic table, a new energy level is added increasing the size of the atoms Ex) of the following, which has the highest and lowest first ionization energy? Answer: Highest- C Lowest- AL

Periodic Trends Of Electron Affinity Electron Affinity tends to decrease as we go from left to right! BUT WHY?!?!?!?!?!?!?!?!?!?!?! This is because the elements on LEFT side of the Periodic Table of LESS valence electrons.

Electron Affinity the energy change when an electron is added to a neutral atom to from a negative ion ACROSS- increase DOWN- decrease

Continue? The elements on the right, are one electron away from GETTING A FULL OCTET! They will have a high affinity, so they can gain the last electron. (The more negative the electron affinity, the greater the attraction for an electron)

METALS!!! Woohooo Metals are the shiny things we have learned to love and treasure They are ductile, conduct heat and electricity, and malleable. They are all solid (except Mercury!) at room temperature. They can have high melting points, for example Chromium has a melting point at 1900 C.

Metals, CONTINUED! Metals have low ionization energies (energy required to remove an valence electron) WHICH MEANS, they tend to form positive ions EASILY!!!!!!! Because of this… when metals go through CHEMICAL REACTIONS they are OXIDIZED

But what does oxidized mean?!?! An metal has been OXIDIZED when it loses electrons. Metals are oxidized by many different substances INCLUDING OXYGEN GAS (O2) and ACIDS!

Alkali and Alkaline Earth Metals The charge of ALL alkali metals is ALWAYS 1+ The charge of ALL alkaline earth metals is always 2+

Transition Metals! Many transition metals have a +2 charge, BUT +2 AND +3 is also encountered! A characteristic of the Transition elements is to be able to form ions!

NONMETALS! Nonmetals are overall worse than metals  They are not lustrous and are generally poor conductors of heat and electricity. They have a lower melting point than those of metals, BUTT the diamond form of carbon melts at 3570 C

Nonmetals, CONTINUED! UNDER ORDINARY CONDITION: Seven elements of the nonmetals exist in diatomic elements ****BrNClHOF**** Because of their ELECTRON AFFINITY, nonmetals tend to GAIN ELECTRONS when they react with metals.

Compounds composed entirely of nonmetals are molecular substances Ex: Oxides, Halides, and Hydrides

METALLOIDS Properties of Metalloids include propertis from both Metals and Nonmetals Ex: Silicon is shiny like a metal, but is brittle like a nonmetal

Group Trends of Active Metals! Group 1A Alkali Metals Soft, metallic solids Shiny, and have a high thermal electrical conductivity. Low density, and low melting points. As you move down the group, the atomic radius increases, and ionization energy decreases

Alakali metals are extremely reactive toward WATER and OXYGEN Alkali Metal Ions are colorless and produce a characteristic a color when combusted EX: Burning sodium produces a yellow flame.

Group 2A: Alkaline Earth Metals Ionization energies of these metals are low, but not as low as the alkali metals They are less reactive then the 1A Metals The “heavier” alkaline earth metals are more reactive than the lighter ones

Group Trends for Non Metals Hydrogen: Even though Hydrogen is in the Alkali metals, it does not belong to any specific group However, Hydrogen can have metallic properties under extreme pressure Ex: the center of Saturn is surrounded by a thick shell of pressurized Hydrogen

Group 6A: The Oxygen Group In the 6A group, there is a change from non-metallic to metallic character Oxygen through Selenium are non-metals and Tellurium has some metallic properties

Group 7A: Halogens The Halogens are tpically nonmetals Their melting and boiling points increase as they go down the coloumn. Halogens, have ridiculously high electron afifnities, this is because they really want to get ONE MORE ELECTRON, to mimic the Noble Gasses.

Noble Gasses All gasses at room temperature. Because of their stable and filled outer orbitals, they are extremely un-reactive