Transcript Electrons
PERIODIC TABLE TRENDS 1 2 3 PERIODIC TABLE UNIT 4 Dimitri Mendeleev Arranged the periodic table in order of increasing atomic mass. 5 The modern periodic table is arranged by increasing atomic number. 6 Horizontal Rows 7 VERTICAL COLUMNS Work Session • First: complete Vocab assignment and turn in. Trends on Periodic Tables • Metal/Nonmetal/Metalloid • Solid/Liquid/Gas • Ending Orbitals • Families For each table, use different colors to illustrate the trends. BE SURE TO INCLUDE A KEY! QUIZ TOMORROW!! Families: Alkali Metals Alkaline Earth Metals Transition Metals Other Metals Metalloids Other Nonmetals Halogens Noble Gases 8 9 Metals, Nonmetal, or Metalloids 10 Solid, Liquid, or Gas Electron Configuration Ending Orbitals (s,p,d,f) 11 12 • • • • Atomic Radii Ionic Radii Ionization energy Electronegativity DEFINITION The distance from the center of the nucleus to the furthest orbital in neutral atoms. ATOMIC RADII TRENDS GROUP TREND AR increases going down the group PERIOD TREND AR decreases going right in a period EXPLANATION AR becomes larger going down a group because there are more energy levels. AR becomes smaller going right in a period because the nucleus has more positive pull holding the electrons closer. EXAMPLES Put the following elements in order of largest to smallest atomic radii: Mg, Cl, Na, P Order of AR: EXAMPLES Put the following elements in order of largest to smallest atomic radii: Mg, Cl, Na, P Order of AR: Na>Mg>P>Cl DEFINITION The distance from the center of the nucleus to the furthest orbital in a charged atom. IONIC RADII G RO U P T R E N D There is a gradual increase of ionic radii going down a group. TRENDS PERIOD TREND Ionic radii decrease going right in a period. EXPLANATION Recall that . . . Positive ions are formed by the loss of electrons and are called cations. Cations are smaller than the original atom. Negative ions are formed by the gain of electrons and are called anions. Anions are larger than the original atom. EXAMPLES Put the following ions in order from largest to smallest radii P3- Cl- S-2 EXAMPLES Put the following ions in order from largest to smallest radii P3->S-2>Cl- DEFINITION Ionization energy is the amount of energy required to remove an electron from an element. IONIZATION ENERGY TRENDS GROUP TREND PERIOD TREND Ionization energies decrease down the group because the electrons in the last orbitals are further from the nucleus and thus easier to remove. Ionization energy increases going right in a period because metals (which are on the right) have fewer valence electrons to lose, thus do so more easily. Non metals have more valence electrons therefore tend to gain electrons instead of lose. EXAMPLE Put the following elements in order of largest to smallest ionization energy: Li, Ne, O Order of ionization energy: EXAMPLE Put the following elements in order of largest to smallest ionization energy: Li, Ne, O Order of ionization energy: Ne>O>Li DEFINITION Electronegativity is a measure of the ability of an atom to attract electrons. increase ELECTRONEGATIVITY TRENDS GROUP TREND Electronegativity tends to decrease going down most groups or remain about the same in other groups. PERIOD TREND Electronegativity tends to increase going right in a period. EXPLANATION Atoms seek to have a full outer electron shell. Elements close to having 8 electrons in their outer shell will be highly attractive to new electrons. Elements far from having 8 electrons in their outer shell will be very unattractive to new electrons. EXAMPLES Put these elements in order from largest to smallest electronegativity: Na, P, Cl, Al EXAMPLES Put these elements in order from largest to smallest electronegativity: • Na, P, Cl, Al Cl>P>Al>Na 41 Group 1: Alkali Metals • • • • • Soft and shiny Reacts violently with water Not found in elemental form in nature 1 valence electron Ex: sodium and potassium Lithium reacting with water 42 https://www.youtube.com/watch?v=ODf_sPexS2Q 43 Group 2: Alkaline Earth Metals • Harder, more dense, stronger, and less reactive than alkali metals • 2 valence electrons • Ex: calcium calcium barium 44 45 Groups 3-13: Transition Metals • Can lose electrons to form positive ions • Harder, more dense, and higher melting points • Ex: 46 47 Group 17: Halogens • • • • Seven valence electrons Most reactive nonmetal Combine with metals to form salts Ex: chlorine 48 49 Group 18: Noble Gases • “Inert”—unreactive • Do not form compounds • Ex: helium neon 50