Hello.
The answer i believe would be sodium.
Have a great day.
Explanation:
Helium exists in three different forms due to the phenomenon of isotopy. Isotopy is the existence of two or more atoms of the same element having the same atomic number but different mass numbers due to the differences in the number of neutrons in their nuclei.
- The atoms of these elements are called isotopes.
- This is why Helium can exist in three different forms.
- Isotopes have the same electronic configuration but with the same chemical properties.
Learn more:
isotopes brainly.com/question/1915462
Isotopy brainly.com/question/2593342
#learnwithBrainly
Answer:
solid particles are tightly held.
liquid particles have perfectly inelastic collisions
gas move in constant random motion
vapour
The atoms are rearranged...
atoms AREN'T created or destroyed
Hydrogen (H) 1s1
2 Helium (He) 1s2
3 Lithium (Li) [He] 2s1
4 Beryllium (Be) [He] 2s2
5 Boron (B) [He] 2s2 2p1
6 Carbon (C) [He] 2s2 2p2
7 Nitrogen (N) [He] 2s2 2p3
8 Oxygen (O) [He] 2s2 2p4
9 Fluorine (F) [He] 2s2 2p5
10 Neon (Ne) [He] 2s2 2p6
11 Sodium (Na) [Ne] 3s1
12 Magnesium (Mg) [Ne] 3s2
13 Aluminium (Al) [Ne] 3s2 3p1
14 Silicon (Si) [Ne] 3s2 3p2
15 Phosphorus (P) [Ne] 3s2 3p3
16 Sulphur (S) [Ne] 3s2 3p4
17 Chlorine (Cl) [Ne] 3s2 3p5
18 Argon (Ar) [Ne] 3s2 3p6
19 Potassium (K) [Ar] 4s1
20 calcium (ca) [Ar] 4s2