17. explain the significance of the stair - step line located near the right - hand side of the periodic…

17. explain the significance of the stair - step line located near the right - hand side of the periodic table.\n18. the process by which the core electrons partially block the attraction between the nucleus and the valence electrons is called __________.\n19. a positively charged ion is called a(n) ___. a negatively charged ion is called a(n) ___.\n20. what are main group or representative elements?\n21. identify the main group elements from the following list: na, ca, sc, co, ni, si, n, se, cl, ge\n22. period 3 elements - all of them\n a. write the electron configuration.\n b. draw the orbital diagram.\n c. indicate the number of valence electrons and draw dot diagram.\n23. the most stable type of electron configuration.

17. explain the significance of the stair - step line located near the right - hand side of the periodic table.\n18. the process by which the core electrons partially block the attraction between the nucleus and the valence electrons is called __________.\n19. a positively charged ion is called a(n) ___. a negatively charged ion is called a(n) ___.\n20. what are main group or representative elements?\n21. identify the main group elements from the following list: na, ca, sc, co, ni, si, n, se, cl, ge\n22. period 3 elements - all of them\n a. write the electron configuration.\n b. draw the orbital diagram.\n c. indicate the number of valence electrons and draw dot diagram.\n23. the most stable type of electron configuration.

Answer

Brief Explanations:

  1. The stair - step line on the right - hand side of the periodic table separates metals from non - metals. Elements to the left are metals, to the right are non - metals, and along the line are metalloids with properties intermediate between metals and non - metals.
  2. The process is called shielding or screening. Core electrons repel valence electrons, reducing the effective nuclear charge experienced by valence electrons.
  3. A positively charged ion is called a cation. A negatively charged ion is called an anion.
  4. Main group or representative elements are those in groups 1, 2 and 13 - 18. They have their outermost electrons in s or p orbitals and show a wide range of chemical properties.
  5. Main group elements from the list are Na (Group 1), Ca (Group 2), Si (Group 14), N (Group 15), Se (Group 16), Cl (Group 17). Sc is a transition metal and Co, Ni are also transition metals, Ge is a post - transition metal but also considered a main group element in some contexts.
  6. Period 3 elements are Na, Mg, Al, Si, P, S, Cl, Ar.
    • a. Na: $1s^{2}2s^{2}2p^{6}3s^{1}$; Mg: $1s^{2}2s^{2}2p^{6}3s^{2}$; Al: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}$; Si: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{2}$; P: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$; S: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{4}$; Cl: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}$; Ar: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}$
    • b. Orbital diagrams follow the Aufbau principle, Pauli exclusion principle, and Hund's rule. For example, for Na, the 1s orbital has 2 electrons with opposite spins, 2s has 2 electrons with opposite spins, 2p has 6 electrons (3 pairs), and 3s has 1 electron with a single spin.
    • c. Na has 1 valence electron, Mg has 2, Al has 3, Si has 4, P has 5, S has 6, Cl has 7, Ar has 8. Dot diagrams show the number of valence electrons as dots around the element symbol.
  7. The most stable type of electron configuration is a noble - gas configuration, where the outermost shell is completely filled (s²p⁶ for the main group elements in periods 2 and up, or s² for helium).

Answer:

  1. Separates metals from non - metals and metalloids are along it.
  2. Shielding or screening
  3. Cation; Anion
  4. Elements in groups 1, 2 and 13 - 18 with outermost electrons in s or p orbitals.
  5. Na, Ca, Si, N, Se, Cl
    • a. Na: $1s^{2}2s^{2}2p^{6}3s^{1}$, Mg: $1s^{2}2s^{2}2p^{6}3s^{2}$, Al: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}$, Si: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{2}$, P: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$, S: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{4}$, Cl: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}$, Ar: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}$
    • b. Diagrams follow Aufbau, Pauli, and Hund's rules.
    • c. Na: 1 valence electron, Mg: 2, Al: 3, Si: 4, P: 5, S: 6, Cl: 7, Ar: 8; Dot diagrams show valence electrons as dots.
  7. Noble - gas configuration.