Chapter 5 The Periodic Table Periodic Table Info Periodic Table Development Dimitri Mendeleev (1834 – 1907) • Arranged the elements by increasing ATOMIC MASS • Produced the first PERIODIC TABLE – 1871 • The table placed elements with similar properties in the same column • Kept “holes” for undiscovered elements, and predicted the properties in advance Mendeleev’s Periodic Table Predicting Properties New Periodic Table H. G. Moseley (1887-1915) • Rearranged the elements by ATOMIC NUMBER • This is the MODERN PERIODIC TABLE What’s on the Periodic Table? • atomic number • symbol • name • average atomic mass • electron configuration Reading the Periodic Table • GROUP: vertical column (family) similar chemical properites • PEROID: horizontal row same filled energy levels 1 2 3 5 6 7 Period Group 4 Periodic Table Groups Properties of Metals 1. 2. 3. 4. shiny (luster) conductors of heat and electricity Reactive with acids ductile – can be stretched into a wire 5. malleable – can be hammered or rolled into sheets Properties of Nonmetals 1. 2. 3. 4. Dull and brittle poor conductors of heat and electricity Does not react with acids usually gases at room temp. PERIODIC LAW • When elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic (repeating) pattern. Which means: • there are patterns across the periodic table called periodic trends Atomic Radius half the distance from center-center of 2 like atoms Atomic Radii DOWN a Group ↓ As you go down a group another energy level is added, the atom size gets larger Atomic Radius: down group P X X Na P P P P P P P P P P P X X X X X X X X X X Atomic Radius: down group P X X K P P P P P P P P P P P X X X X X X X X X X X X X X X X X X Atomic Radii DOWN a Group ↓ DOWN THE GROUP ATOMIC RADIUS INCREASES more energy levels, the larger the size of the atom Atomic Radii ACROSS a Period → Each atom gains one proton and one electron in the same energy level →Each added electron is the same distance from the nucleus →The positive charge increases and exerts a greater force on the electrons thereby pulling it closer to the nucleus REMEMBER! PROTONS are bigger and stronger! + e + P -electrons are smaller and weaker! Atomic Radius: across period P X X X X X P P X P P P P P P P X P X X X X Atomic Radii ACROSS a Period →ACROSS THE PERIOD ATOMIC RADIUS DECREASES stronger attraction of protons, easier to hold on to the electrons Ionization Energy amount of energy needed to remove an electron from an atom Ion: an atom that has gained or lost electrons if you lose an electron… if you gain an electron… BECOMES POSITIVE! BECOMES NEGATIVE! Ionization Energy DOWN a Group ↓ As you go down a group atoms become larger, electrons are farther from the nucleus and more easily removed Ionization Energy DOWN a Group ↓ DOWN THE GROUP IONIZATION ENERGY DECREASES greater distance from the nucleus, the easier to lose an electron (less energy needed) Ionization Energy ACROSS a Period →As atomic radius decreases there is a greater attraction between protons and electrons. →The stronger the attraction, the more energy needed to remove an electron. →The more electrons present, the more energy required to remove them all to become STABLE Ionization Energy ACROSS a Period →ACROSS THE PERIOD IONIZATION ENERGY INCREASES more electrons on an energy level, more energy required to remove them all Electronegativity tendency for an atom to attract electrons It is a “tug of war” between the two . atoms of a bond : : . H . F : Which is the more electronegative element? Electronegativity ACROSS the Period →As you go across a period atomic radius decreases because there is a greater attraction between protons and electrons →Metals do not attract electrons. →Non-metals do attract electrons. Electronegativity ACROSS the Period →ACROSS THE PERIOD ELECTRONEGATIVITY INCREASES stronger the attraction, the easier to add more electrons Electronegativity DOWN the Group ↓ The larger the atom, the less likely it is to accept more electrons. Electronegativity DOWN the Group ↓ DOWN THE GROUP ELECTRONEGATIVITY DECREASES farther the distance from the nucleus, more difficult to attract electrons PUT IT ALL TOGETHER! Reactivity of Alkali Metals Where are the most reactive metals? Where are the most reactive nonmetals? Activity Series of the Elements 1.Why is sodium not used for silverware? It is highly reactive and reacts with water. 2. Why has so much gold jewelry survived from ancient civilizations? It does not react with oxygen or water and therefore does not readily break down. 3. Why is food canned in containers made from steel coated with a thin layer of tin? Steel makes a strong container and the tin lining does not react with the contents. 4. Why are cars painted? To prevent the iron from rusting by being exposed to oxygen in air.