Question

directions: select the correct element on the periodic table. select the element with the highest number of electrons in its outer shell. choose from the elements highlighted in blue. periodic table elements (highlighted in blue: li, p, kr, sr, pb) and their details as per the table structure: li (5.940), be (9.012), b (10.81), c (12.01), n (14.01), o (16.00), f (19.00), ne (20.18); na (22.99), mg (24.31), al (26.98), si (28.09), p (30.97), s (32.06), cl (35.45), ar (39.95); k (39.10), ca (40.08), sc (44.96), ti (47.88), v (50.94), cr (52.00), mn (54.94), fe (55.85), co (58.93), ni (58.69), cu (63.55), zn (65.39), ga (69.72), ge (72.64), as (74.92), se (78.96), br (79.90), kr (83.79); rb (85.47), sr (87.62), y (88.92), zr (91.22), nb (92.91), mo (95.96), tc (96), ru (101.1), rh (102.9), pd (106.4), ag (107.9), cd (112.4), in (114.8), sn (118.7), sb (121.8), te (127.6), i (126.9), xe (131.3); cs (132.9), ba (137.3), hf (178.5), ta (180.9), w (183.9), re (186.2), os (190.2), ir (192.2), pt (195.1), au (197.0), hg (200.5), tl (204.4), pb (207.2), bi (209.0), po (209), at (210), rn (222); fr (223), ra (226), rf (265), db (268), sg (271), bh (270), hs (277), mt (276), ds (281), rg (280), cn (285), uut (284), fl (289), uup (288), lv (293), uus (294), uuo (294); la (138.9), ce (140.1), pr (140.9), nd (144.2), pm (145), sm (150.4), eu (152.0), gd (157.2), tb (158.9), dy (162.5), ho (164.9), er (167.3), tm (168.9), yb (173.0), lu (175.0); ac (227), th (232.0), pa (231.0), u (238.0), np (237), pu (244), am (243), cm (247), bk (247), cf (251), es (252), fm (257), md (258), no (259), lr (262)

Explanation:

Step1: Recall electron shell rules

For main - group elements (groups 1, 2, 13 - 18), the number of valence (outer - shell) electrons is related to the group number. Group 1 elements have 1 valence electron, group 2 has 2, group 13 has 3, group 14 has 4, group 15 has 5, group 16 has 6, group 17 has 7, and group 18 (noble gases, except He) has 8 valence electrons. He has 2 valence electrons.

Step2: Identify the blue - highlighted elements and their groups

• Li (Lithium): Group 1, valence electrons = 1
• P (Phosphorus): Group 15, valence electrons = 5
• Kr (Krypton): Group 18, valence electrons = 8
• Sr (Strontium): Group 2, valence electrons = 2
• Pb (Lead): Group 14, valence electrons = 4

Step3: Compare the number of valence electrons

Among 1 (Li), 5 (P), 8 (Kr), 2 (Sr), and 4 (Pb), 8 is the highest number of valence electrons.

Answer:

Kr (Krypton)