The Modern Periodic Table 1. An arrangement of the elements in order of their numbers so that elements with properties fall in the same column (or group). Groups: vertical columns (#1-18) Periods: horizontal rows (# 1-7) 2. Periodicity the of the elements in the same group is explained by the arrangement of the around the nucleus. The s- block Elements: 1. Group 1: Alkali metals - ns 1 silvery metals; most of all metals, never found free in nature; reacts with to form alkaline or basic solutions; stored under ; whenever you mix Li, Na, K, Rb, Cs, or Fr with water it will and produce an alkaline solution 2. Group2: Alkaline earth metals- ns 2 reactive than Alkali, but still react in water to produce an solution; never found in nature; harder, denser, stronger than alkali; The d- Block Elements: Transition Metals - Groups 3-12- nd They are all with properties (malleability, luster, good conductors, etc ); are referred to as the and than alkali or alkaline; less than alkali or alkaline; for the most part their outermost electrons are in a d sublevel; exceptions to the electron configuration are found in these groups (Ex: Ni, Pd, Pt) The p Block Elements: Groups 13 18 np Contain and ;, along zigzag line, have characteristics of metals and nonmetals (many are conductors but are ). The metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Group 17 - Halogens most reactive nonmetals- np 5 electrons in outermost (s and p) energy levels (that is why so only need one electron to have 8); called the formers (they react vigorously with metals to form salts). A salt is a ion and a ion bonded together. Most are. Group 18 - Noble gases unreactive- np 6 electrons in outermost s and p energy levels; all are. The f- Block Elements: Inner Transition Metals electrons fill an f sublevel Lanthanides shiny metals; Ce- Lu (fill the 4f sublevel) Actinides and ; Th- Lr (fill the 5f sublevel) Hydrogen and Helium - Oddballs Hydrogen is NOT an Alkali metal; it is a very gas. It is placed with the Alkali metals because 1s 1 is its electron configuration. Helium is a Noble gas, it is, but it does not have 8 electrons in outermost energy level, because it only has 2 total electrons!
Trend in Atomic Radii Atomic Radius Atomic radius is the distance from the centre of the nucleus of an atom to the outermost electron. The size of an atomic radius cannot be measured exactly because it does not have a defined boundary. However the atomic radius can be thought of as the distance between the nuclei of identical atoms joined in a molecule. The greater the number of energy levels the is the distance of the outermost electron to the center of its atom s nucleus. Group trend - atomic radii as you move up a group. Period trend atomic radii as you move across a period. Ionic Radius Ionic radius is the distance from the centre of the nucleus of an to the outermost electron. Cations will have a ionic radius than the neutral atom. Anions will have a ionic radius than the neutral atom. Force of Attraction: The force of attraction between negatively charged electrons and the positively charged nucleus is the attraction of opposite charges. The force of attraction existing between the outermost electron and the middle of the nucleus is dependent on two factors: 1. The of the positive charge - determined by the number of protons in the nucleus. 2. The between the outermost electron and the nucleus. A balance exists between the of the electrons to the nucleus and the of the electrons between themselves Ionization Energy (IE) Ionization Energy is the energy in kilojoules per mole (kj/mol) needed to the outermost electron from a gaseous atom to form a ion (cation). Na + Energy Na + + e - NOTE: Metals react to electrons. The stronger an electron is held the the IE needed to ionize (pull away) that electron Trend: Ionization Energy (IE) Group trend ionization energy as you move a group (or as you move a group). Period trend Ionization energy as you move across the period ( left to right). Example: Which atom has the higher first ionization energy? Hf or Pt. Explain. Example: Which atom has the higher first ionization energy? Cl or Ar. Explain.
Electron Affinity [EA] Electron affinity is the energy in kilojoules per mole (kj/mol) when an electron is by an atom to form a ion (anion). Cl + Electron Cl - + Energy NOTE: Nonmetals react to electrons Trend: Electron Affinity (EA) Period trend electron affinity as you move across a Period because atoms become and the nuclear charge. This means there is a greater pull from the nucleus. Group trend electron affinity as you move a group (or as you move a group) because the size of the atom. Example: Which element has the greater electron affinity? Pb or Sn. Explain Electron affinity vs. Ionization energy Electron affinity and Ionization energy follow the same trend in the periodic table. The the attraction an atom has for electrons the it will be to remove electrons from that atom and the the IE energy will be. The the attraction for electrons the the energy released when an atom gains an electron. Electronegativity [EN} Electronegativity is a measure of the of an atom to gain electrons when it is chemically combined (bonded) to another element. The the pull or attraction of electrons to an atoms nucleus, the its tendency to gain electrons. In general, metals have EN and nonmetals have EN. The actual amount of EN an atom has is indicated by a number of the Pauling Electronegativity Scale that goes from 0 to 4. Dr. Linus Pauling set up this scale and gave the element having the greatest EN an arbitrary number of 4, and he assigned numbers to the others relative to this element. Trend: Period trend - EN as you go across a period (excluding the noble gases) because size. Group trend - EN as you go a group because there is pull from the nucleus as the electrons get further away. Example: Which would have the greater EN? Ca or Se. Explain.
Electronegativity enables us to predict what of bond will be formed when two elements combine. Reactivity of Nonmetals Reactivity - how a substance reacts with another. Metals lose electrons (Ionization Energy) Nonmetals gain electrons (Electron Affinity) Trends: Group Trend: Period Trend: EFFECTIVE NUCLEAR CHARGE (ENC) AND SHIELDING Element Na Mg Al Si P S Cl Ar # of electrons # of valance electrons # of protons # of inner electrons ENC
The force of attraction between charged protons in the nucleus and charged electrons is the force that holds atoms together. The inner electrons (not in the outermost energy level) in inner energy levels, partially or the attraction of the protons from the outer electrons in the outermost energy level (VALENCE ELECTRONS). The canceling of the positive nuclear charge is called. EFFECTIVE NUCLEAR CHARGE (ENC) is a number assigned to elements to describe the amount of shielding by the valence electrons. ENC = Number of - Number of electrons The greater the ENC the the valence electrons are shielded and the the pull on the valence electrons. Greater ENC will mean a atomic radius. Shielding will help explain some of the trends in the periodic table SUCCESSIVE IONIZATION ENERGIES The first ionization energy is the energy required to remove the electron (First IE). It is relatively low because of the repulsion exerted by the other electrons. Each successive Ionization energy (Second and Third IE and so on) will. It becomes difficult to remove successive electrons since the pull of the nucleus becomes (greater number of protons relative to the electrons) and the electrons are tightly held Ionic radius becomes. There will be a jump in the increase of IE once the gas configuration has been reached. This is because outer energy level has been (radius is smaller) Example 1: Consider the following Ionization Energies for an element X: How many valance electrons does this element have? Explain. 1 st 2 nd 3 rd 4 th 5 th 2.38 kj 2.54 kj 22.48 kj 25.88 kj 28.35 kj Example 2: Where would the large increase in I.E. occur for Se? Explain your answer.
Periodic Table Trends Worksheet 4. Which main group elements have 1 valence electron? 6 valence electrons? 5. Without looking at the periodic table determine the group, period, and block for the following elements: a. [Ne]3s 1 block group period b. [Ar]4s 2 3d 10 block group period c. [Ar]4s 2 3d 10 4p 2 block group period d. [Kr]5s 2 4d 2 block group period e. [Kr]5s 2 4d 10 block group period 6. Use their placement on the periodic table to arrange the following elements based on their size (atomic radii) from largest to smallest. a. Ca, Ge, Br, K, Kr b. Sr, Mg, Be, Ba, Ra c. F, Cl, Fr, Cs 7. Use their placement on the periodic table to arrange the following elements from highest ionization energy to lowest ionization energy. a. Ca, Ge, Br, K, Kr b. Sr, Mg, Be, Ba, Ra c. F, Cl, Fr, Cs 8. Use their placement on the periodic table to determine which of the following has a higher electron affinity. a. F or Sn b. Si or Y c. Fe or K d. Bi or N e. Ho or Br f. Rb or Cl 9. Use their placement on the periodic table to determine which of the following has a lower electronegativity. a. F or Sn b. Si or Y c. Fe or K d. Bi or N e. Ho or Br f. Rb or Cl 10. Use their placement on the periodic table to determine which of the following is smaller. a. Ca atom or Ca ion b. Cl atom or Cl ion c. N ion or O ion Mg ion or Sr ion 11. Which of the following has the most shielding? a. Br or F b. Al or Cl or neither c. Ca or Ra 12. When sodium becomes an ion electrons are (lost/gained). 13. When aluminum ionizes, electrons are. Nitrogen ionizes and electrons are. 14. An ion that has a charge of +2 with 20 protons is the ion. It has electrons and neutrons. 15. The ion that has a - 3 charge with 19 electrons is 16. The ion that has a +3 charge with 26 protons is. 4. Alkali Metals, Group 16 5. a. s,1,3 b. d,12,4 c. p,14,4 d. d,4,5 e. d,12,5 6. a. K,Ca,Ge,Br,Krb. Ra,Ba,Sr,Mg,Be c. Fr,Cs,Cl,F 7. a. Kr,Br,Ge,Ca,K b. Be,Mg,Sr,Ba,Ra c. F,Cl,Cs,Fr 8. a. F b. Si c. Fe d. N e. Br f. Cl 9. a. Sn b. Y c. K d. Bi e. Ho f. Rb 10. a. Ca ion b. Cl atom c. O ion d. Mg ion 11. a. Br b. neither c. Ra 12. 1, lost 13. 3, lost, 3, gained 14. Ca 2+,18,20 15. S 3-16. Fe 3+