elements.js

const elements = `1,H,Hydrogen,1.00794
2,He,Helium,4.002602
3,Li,Lithium,6.941
4,Be,Beryllium,9.012182
5,B,Boron,10.811
6,C,Carbon,12.0107
7,N,Nitrogen,14.0067
8,O,Oxygen,15.9994
9,F,Fluorine,18.9984032
10,Ne,Neon,20.1797
11,Na,Sodium,22.98976928
12,Mg,Magnesium,24.305
13,Al,Aluminum or Aluminium,26.9815386
14,Si,Silicon,28.0855
15,P,Phosphorus,30.973762
16,S,Sulfur,32.065
17,Cl,Chlorine,35.453
18,Ar,Argon,39.948
19,K,Potassium,39.0983
20,Ca,Calcium,40.078
21,Sc,Scandium,44.955912
22,Ti,Titanium,47.867
23,V,Vanadium,50.9415
24,Cr,Chromium,51.9961
25,Mn,Manganese,54.938045
26,Fe,Iron,55.845
27,Co,Cobalt,58.933195
28,Ni,Nickel,58.6934
29,Cu,Copper,63.546
30,Zn,Zinc,65.38
31,Ga,Gallium,69.723
32,Ge,Germanium,72.64
33,As,Arsenic,74.9216
34,Se,Selenium,78.96
35,Br,Bromine,79.904
36,Kr,Krypton,83.798
37,Rb,Rubidium,85.4678
38,Sr,Strontium,87.62
39,Y,Yttrium,88.90585
40,Zr,Zirconium,91.224
41,Nb,Niobium,92.90638
42,Mo,Molybdenum,95.96
43,Tc,Technetium,98
44,Ru,Ruthenium,101.07
45,Rh,Rhodium,102.9055
46,Pd,Palladium,106.42
47,Ag,Silver,107.8682
48,Cd,Cadmium,112.411
49,In,Indium,114.818
50,Sn,Tin,118.71
51,Sb,Antimony,121.76
52,Te,Tellurium,127.6
53,I,Iodine,126.90447
54,Xe,Xenon,131.293
55,Cs,Cesium,132.9054519
56,Ba,Barium,137.327
57,La,Lanthanum,138.90547
58,Ce,Cerium,140.116
59,Pr,Praseodymium,140.90765
60,Nd,Neodymium,144.242
61,Pm,Promethium,145
62,Sm,Samarium,150.36
63,Eu,Europium,151.964
64,Gd,Gadolinium,157.25
65,Tb,Terbium,158.92535
66,Dy,Dysprosium,162.5
67,Ho,Holmium,164.93032
68,Er,Erbium,167.259
69,Tm,Thulium,168.93421
70,Yb,Ytterbium,173.054
71,Lu,Lutetium,174.9668
72,Hf,Hafnium,178.49
73,Ta,Tantalum,180.94788
74,W,Tungsten,183.84
75,Re,Rhenium,186.207
76,Os,Osmium,190.23
77,Ir,Iridium,192.217
78,Pt,Platinum,195.084
79,Au,Gold,196.966569
80,Hg,Mercury,200.59
81,Tl,Thallium,204.3833
82,Pb,Lead,207.2
83,Bi,Bismuth,208.9804
84,Po,Polonium,209
85,At,Astatine,210
86,Rn,Radon,222
87,Fr,Francium,223
88,Ra,Radium,226
89,Ac,Actinium,227
90,Th,Thorium,232.03806
91,Pa,Protactinium,231.03588
92,U,Uranium,238.02891
93,Np,Neptunium,237
94,Pu,Plutonium,244
95,Am,Americium,243
96,Cm,Curium,247
97,Bk,Berkelium,247
98,Cf,Californium,251
99,Es,Einsteinium,252
100,Fm,Fermium,257
101,Md,Mendelevium,258
102,No,Nobelium,259
103,Lr,Lawrencium,262
104,Rf,Rutherfordium,267
105,Db,Dubnium,268
106,Sg,Seaborgium,271
107,Bh,Bohrium,272
108,Hs,Hassium,270
109,Mt,Meitnerium,276
110,Ds,Darmstadtium,281
111,Rg,Roentgenium,280
112,Cn,Copernicium,285
113,Uut,Ununtrium,284
114,Uuq,Ununquadium,289
115,Uup,Ununpentium,288
116,Uuh,Ununhexium,293
117,Uus,Ununseptium,
118,Uuo,Ununoctium,294`

function toElement(n) {
  const [number, symbol, name, weight] = n.split(',')
  return {number, symbol, name, weight: Number(weight)}
}

elements.match(/.+/g)
  .map(toElement)
  .filter(({name, weight}) => weight > 50 && weight < 100 && name.slice(-3) != 'ium')
  .forEach(({name}) => console.log(name))