Question

match the description to the element
alkali metal with an atomic number of 19
most common mass number is 70
halogen with the smallest atomic mass
noble gas with 6 electron energy levels
family 6 and series 4
6 valence electrons in the 6th energy level
in the same period as platinum and the same group as beryllium
mass number of 17 with 9 neutrons
244 is its most stable isotope
metalloid with 4 valence electrons with the smallest atomic mass
gas in group 16
gas in group 1

Answer:

1. Alkali metal with atomic number 19

• Atomic number 19 means 19 protons. Alkali metals are Group 1. Element: K (Potassium).

2. Most common mass number 70

• Mass number = protons + neutrons. For Ga (Gallium), common isotopes include Ga - 70. Check: Ga has 31 protons, 70 - 31 = 39 neutrons (stable isotope).

3. Halogen with smallest atomic mass

• Halogens are Group 17. Smallest atomic mass: F (Fluorine, atomic mass ~19).

4. Noble gas with 6 electron energy levels

• Noble gases: Group 18. 6 energy levels → Period 6. Element: Rn (Radon, period 6, group 18).

5. Family 6 and series 4

• Family (group) 6, series (period) 4. Element: Cr (Chromium, period 4, group 6).

6. 6 valence electrons in 5th energy level

• 5th energy level (period 5), 6 valence electrons (group 16). Element: Te (Tellurium, period 5, group 16).

7. Same period as platinum, same group as beryllium

• Platinum (Pt) is period 6. Beryllium (Be) is group 2. Period 6, group 2: Ba? No, period 6 group 2 is Ra? Wait, Pt is period 6. Group 2, period 6: Radium (Ra)? Wait, Be is group 2 (alkaline earth). Period 6, group 2: Ra. Wait, Pt is period 6 (atomic number 78). Group 2, period 6: Ra (atomic number 88). Wait, maybe Ca? No, Pt is period 6. Wait, maybe Sr? No. Wait, correction: Platinum is period 6. Beryllium is group 2. So element in period 6, group 2: Radium (Ra). Wait, but maybe Ba? No, Ba is period 6? No, Ba is period 6? Ba is period 6? Ba: atomic number 56, period 6? Wait, period 1: H, He; period 2: Li - Ne; period 3: Na - Ar; period 4: K - Kr; period 5: Rb - Xe; period 6: Cs - Rn. So Pt (78) is period 6. Group 2: Be (4), Mg (12), Ca (20), Sr (38), Ba (56), Ra (88). So period 6, group 2: Ra (88).

8. Mass number 17, 9 neutrons

• Mass number = protons + neutrons → protons = 17 - 9 = 8. Element with 8 protons: O (Oxygen). Isotope: O - 17 (protons 8, neutrons 9).

9. Most stable isotope 244

• Element with stable isotope 244: Pu? No, Pu - 244 is a isotope, but maybe Cm? Wait, maybe Pu (Plutonium) or Cm (Curium). Wait, 244: atomic mass 244. Let’s check: Atomic number = 244 - neutrons. Wait, maybe Pu - 244 (atomic number 94, neutrons 244 - 94 = 150). Or Cm - 244 (atomic number 96, neutrons 244 - 96 = 148). But maybe the element is Pu? Wait, maybe the answer is Pu (Plutonium) with isotope 244.

10. Metalloid with 4 valence electrons, smallest atomic mass

• Metalloids: B, Si, Ge, As, Sb, Te, Po. 4 valence electrons: group 14. Smallest atomic mass: Si? No, B is group 13 (3 valence). Si: group 14, 4 valence, atomic mass ~28. Ge: ~73. So Si is metalloid (some consider Si as metalloid) with 4 valence, smallest atomic mass. Wait, B is group 13 (3 valence). So Si (silicon) is group 14, 4 valence, metalloid, smallest atomic mass in group 14 metalloids.

11. Gas in group 16

• Group 16: O, S, Se, Te, Po. Gases: O (oxygen, O₂) and S? No, S is solid. So O (oxygen) is gas in group 16.

12. Gas in group 1

• Group 1: H, Li, Na, K, etc. Gas: H (Hydrogen, H₂) is gas in group 1.

Final Matches (Key Answers):

1. Alkali metal (Z=19) → K (Potassium)
2. Mass number 70 → Ga (Gallium)
3. Smallest halogen → F (Fluorine)
4. Noble gas (6 levels) → Rn (Radon)
5. Group 6, Period 4 → Cr (Chromium)
6. 6 valence (5th level) → Te (Tellurium)
7. Period 6, Group 2 → Ra (Radium)
8. Mass 17, 9 neutrons → O (Oxygen, O - 17)
9. Isotope 244 → Pu (Plutonium, Pu - 244) (or Cm, but Pu is common)
10. Metalloid (4 valence, smallest) → Si (Silicon)
11. Gas (Group 16) → O (Oxygen, O₂)
12. Gas (Group 1) → H (Hydrogen, H₂)

(Note: Some matches may require periodic table reference for exact element names/symbols.)