Presentation on theme: "1/8/09 Warm Up: The observed regularities in the properties of the elements are periodic functions of their Atomic numbers Mass numbers Oxidation states."— Presentation transcript:
1 1/8/09 Warm Up:The observed regularities in the properties of the elements are periodic functions of theirAtomic numbersMass numbersOxidation statesNonvalence electrons
2 Pop QuizElements in Mendeleev’s periodic table were arranged according to theirAtomic numberAtomic massRelative activityRelative size
3 2. Most of the groups of the periodic table of elements contain Nonmetals onlyMetals onlyNonmetals and metalsMetals and metalloids
4 3. An element is a gas at room temperature. It could be A metal or a metalloidA metal or a nonmetalA metalloid or a nonmetalA nonmetal only
5 4. Atoms of metals tend toLose electrons and form negative ionsLose electrons and form positive ionsGain electrons and form negative ionsGain electrons and form positive ions
6 5. Which property is generally characteristic of metallic elements? Low electrical conductivityHigh heat conductivityExistence as brittle solidsExistence as molecular solids
7 6. When a potassium atom reacts with a bromine atom, the bromine atom will Lose only 1 electronLose 2 electronsGain only 1 electronGain 2 electrons
8 7. At room temperature, potassium is classified as A metallic solidA molecular solidA network solidan ionic solid
9 8. Which list contains 2 metalloids Ga, Ge, SnSi, P, SC, Si, GeB, C, N
10 9. Which element in period 4 is classified as an active nonmetal? GaGeBrKr
11 10. Which element in period 4 is classified as an active metal? KVBrGe
12 AllotropesBuckyballSome nonmetals can exist in 2 or more forms in the same phaseEXAMPLESCarbonGraphiteDiamondBuckminsterfullereneOxygenO2O3 (Ozone)
14 Trends in Atomic SizeFirst problem: Where do you start measuring from?The electron cloud doesn’t have a definite edge.They get around this by measuring more than 1 atom at a time.
15 Atomic Size}RadiusMeasure the Atomic Radius - this is half the distance between the two nuclei of a diatomic molecule.
16 ALL Periodic Table Trends Influenced by three factors:1. Energy LevelHigher energy levels are further away from the nucleus.2. Charge on nucleus (# protons)More charge pulls electrons in closer. (+ and – attract each other)3. Shielding effect
17 What do they influence?Energy levels and Shielding have an effect on the GROUPNuclear charge has an effect on a PERIOD
18 #1. Atomic Size - Group trends HAs we increase the atomic number (or go down a group). .each atom has another energy level,so the atoms get bigger.LiNaKRb
19 #1. Atomic Size - Period Trends Going from left to right across a period, the size gets smaller.Electrons are in the same energy level.But, there is more nuclear charge.Outermost electrons are pulled closer.NaMgAlSiPSClAr
20 RbKPeriod 2NaLiAtomic Radius (pm)KrArNeH310Atomic Number
21 Ions Some compounds are composed of particles called “ions” An ion is an atom (or group of atoms) that has a positive or negative chargeAtoms are neutral because the number of protons equals electronsPositive and negative ions are formed when electrons are transferred (lost or gained) between atoms
22 Metals tend to LOSE electrons, from their outer energy level IonsMetals tend to LOSE electrons, from their outer energy levelSodium loses one: there are now more protons (11) than electrons (10), and thus a positively charged particle is formed = “cation”The charge is written as a number followed by a plus sign: Na1+Now named a “sodium ion”
23 Nonmetals tend to GAIN one or more electrons IonsNonmetals tend to GAIN one or more electronsChlorine will gain one electronProtons (17) no longer equals the electrons (18), so a charge of -1Cl1- is re-named a “chloride ion”Negative ions are called “anions”
24 #2. Trends in Ionization Energy Ionization energy is the amount of energy required to completely remove an electron (from a gaseous atom).Removing one electron makes a 1+ ion.The energy required to remove only the first electron is called the first ionization energy.
25 Ionization EnergyThe second ionization energy is the energy required to remove the second electron.Always greater than first IE.The third IE is the energy required to remove a third electron.Greater than 1st or 2nd IE.
26 ShieldingThe electron on the outermost energy level has to look through all the other energy levels to see the nucleus.Second electron has same shielding, if it is in the same period
27 Ionization Energy - Group trends As you go down a group, the first IE decreases because...The electron is further away from the attraction of the nucleus, andThere is more shielding.
28 Ionization Energy - Period trends All the atoms in the same period have the same energy level.Same shielding.But, increasing nuclear chargeSo IE generally increases from left to right.
30 Driving ForcesFull Energy Levels require lots of energy to remove their electrons.Noble Gases have full orbitals.Atoms behave in ways to try and achieve a noble gas configuration.
31 Trends in Ionic Size: Cations Cations form by losing electrons.Cations are smaller than the atom they came from – not only do they lose electrons, they lose an entire energy level.Metals form cations.Cations of representative elements have the noble gas configuration before them.
32 Ionic size: Anions Anions form by gaining electrons. Anions are bigger than the atom they came from – have the same energy level, but a greater area the nuclear charge needs to coverNonmetals form anions.Anions of representative elements have the noble gas configuration after them.
33 Ion Group trends Each step down a group is adding an energy level Ions therefore get bigger as you go down, because of the additional energy level.Li1+Na1+K1+Rb1+Cs1+
34 Ion Period TrendsAcross the period from left to right, the nuclear charge increases - so they get smaller.Notice the energy level changes between anions and cations.N3-O2-F1-B3+Li1+Be2+C4+
35 #3. Trends in Electronegativity Electronegativity is the tendency for an atom to attract electrons to itself when it is chemically combined with another element.They share the electron, but how equally do they share it?An element with a big electronegativity means it pulls the electron towards itself strongly!
36 Electronegativity Group Trend The further down a group, the farther the electron is away from the nucleus, plus the more electrons an atom has.Thus, more willing to share.Low electronegativity.
37 Electronegativity Period Trend Metals are at the left of the table.They let their electrons go easilyThus, low electronegativityAt the right end are the nonmetals.They want more electrons.Try to take them away from othersHigh electronegativity.
38 The arrows indicate the trend: Ionization energy and Electronegativity INCREASE in these directions
39 Atomic size and Ionic size increase in these directions: