Electronegativity and Ionization Energy Packet #8 Answers

1) What are valence electrons? Only the electrons found in the very outer energy level

2) What number on the periodic table gives you an element’s valence number? The group # (with the A) at the top of each column

3) Why are the valence electrons important? __ They are involved with bonding and determine an element’s chemical reactivity

Electronegativity (EN) Measures how strongly an atom attracts electrons to itself. Not only holding on to its own but stealing other atoms’ electrons too. (a measurement of how big of a bully they are)

Look at your Lewis structures, why would F (fluorine) have a high electronegativity? ___________________ (Hint: refer to the rules above to answer) F has 7 valence electrons and only needs 1 more to have a full outer energy level and be happy (stable)

Why would K (potassium) have a low electronegativity? Has only 1 valence electron and would really like to lose it, so K gives away electrons (does not steal electrons)

Ionization Energy (IE) The amount of energy needed to remove an electron from an atom. Atoms like the Noble gases are not going to let you take their electrons easily, so the amount of energy needed to remove an electron from a Noble gas, like He or Ne, is very large. Fluorine won’t give up it’s electrons easily either, so it has high IE.

Review Questions 1)What does the period # on the periodic table tell you? The number of energy levels an atom has

2) How many energy levels do these atoms have? a.#92 – U has ____ b. #6 – C has ____ c. #77 – Ir has ____ a. 7b. 2c. 6

3) What is the maximum # of energy levels an atom can have? 7

4) Which energy level gets filled first with electrons? First one – energy levels fill up in order

5) What are valence electrons? 6) What do the group #s tell you? 5) The electrons in the very last energy level of an atom 6) The # of valence electrons

7) How many valence electrons do these atoms have? a. #56 – Ba has _____ b. #82 – Pb has ______ c. #53 – I has _____ a. 2b. 4c. 7

8) How are chemically stable (happy ) atoms different from atoms that are chemically unstable (unhappy  )? 9)Are most atoms chemically stable or unstable? 8) Stable atoms have full outer energy levels and unstable have outer energy levels with space for more electrons 9) Unstable

10. Why don’t the atoms of the noble gases form bonds? They have full outer energy levels and don’t need any more electrons

11. Why do the chemically unstable atoms form bonds? They need to get more electrons by sharing or by trading electrons because they don’t have full outer energy levels

12. Why is F (#9) considered a bully? 13. Why is Ba (#56) considered a wimp? 14. Which group # contains the “socialist” atoms and why? 12. It is 1 electron short of a full energy level and readily steals electrons from any atom willing to give one up 13. Barium gives up its 2 valence electrons very easily 14. Group 4 – because they willing share electrons 13. Barium gives up its 2 valence electrons very easily

15. What is ionization energy? 16. Which atom has the lowest ionization energy and why? 17. Which atom has the strongest ionization energy (hint: it’s not F but close – think about the meaning of “ionization energy”) and why? 15. The amount of energy needed to remove an electron from an atom. 16. Francium, only 1 valence electron and its in the 7 th energy level (so very far from the nucleus – so nucleus has little attraction for it. Easy to steal Francium’s valence electron. 17. He because it has 2 electrons in its 1 st and only energy level (so it’s full). They are right next to the nucleus, so they are very tightly attracted to the nucleus. He will not give up it’s electrons easily.

18. Measures how strongly an atom attracts electrons to itself. Not only holding on to its own but stealing other atoms’ electrons too. (a measurement of how big of a bully they are) 18.What is electronegativity? 19.Which atom has the highest electronegativity and why? 20.Why does O(#8) have a higher electronegativity than Be (#4)? 21.Why don’t the Noble gases have electronegativity? 19. Fluorine because it is one electron away from a full energy level and its valence electrons are very close to its nucleus 20. O has 6 valence electrons (it’s in group 6A) and if it can steal 2 more electrons, it will be stable, whereas Be has 2 valence electrons and it would rather lose its 2 so it can have the same electron pattern as Helium 21. Noble gases have full outer energy levels and DO NOT need more electrons nor do they want them (they are hermits and want to be left alone)

22. Put the atoms in order of largest radius to smallest radius – Y(39), As(33), Cs (55), He (2) and Sc (21). 22. (smallest radii near top right corner of table and largest is bottom left – Francium) Cs  Y  Sc  As  He

23. Why does Sb (51) have a smaller radius than Sr (38) even though Sb has more protons and a higher atomic mass and both have 5 orbitals? 23. Sb has more protons (stronger coulombic attraction) which attract its valence electrons stronger than Sr’s nucleus.