Period 4 elements
Period 4 is the first row where transition metals appear. It runs from potassium to krypton and includes iron, copper, zinc and nickel - the metals that power everything from kitchen knives to electric grids.
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| No. | Symbol | Element | Atomic weight (u) | Density (g/cm³) | Melting point (K) | Boiling point (K) | Electronegativity | Discovered |
|---|---|---|---|---|---|---|---|---|
| 19 | K | Potassium | 39.0983 | 0.862 | 336.7 | 1032 | 0.82 | 1807 |
| 20 | Ca | Calcium | 40.0784 | 1.55 | 1115 | 1757 | 1 | 1808 |
| 21 | Sc | Scandium | 44.9559 | 2.985 | 1814 | 3109 | 1.36 | 1879 |
| 22 | Ti | Titanium | 47.8671 | 4.506 | 1941 | 3560 | 1.54 | 1791 |
| 23 | V | Vanadium | 50.9415 | 6 | 2183 | 3680 | 1.63 | 1801 |
| 24 | Cr | Chromium | 51.9962 | 7.19 | 2180 | 2944 | 1.66 | 1794 |
| 25 | Mn | Manganese | 54.938 | 7.21 | 1519 | 2334 | 1.55 | 1774 |
| 26 | Fe | Iron | 55.8452 | 7.874 | 1811 | 3134 | 1.83 | 5000 BC |
| 27 | Co | Cobalt | 58.9332 | 8.9 | 1768 | 3200 | 1.88 | 1735 |
| 28 | Ni | Nickel | 58.6934 | 8.908 | 1728 | 3003 | 1.91 | 1751 |
| 29 | Cu | Copper | 63.5463 | 8.96 | 1357.77 | 2835 | 1.9 | 9000 BC |
| 30 | Zn | Zinc | 65.382 | 7.14 | 692.68 | 1180 | 1.65 | 1000 BC |
| 31 | Ga | Gallium | 69.7231 | 5.91 | 302.915 | 2673 | 1.81 | 1875 |
| 32 | Ge | Germanium | 72.6308 | 5.323 | 1211.4 | 3106 | 2.01 | 1886 |
| 33 | As | Arsenic | 74.9216 | 5.727 | - | - | 2.18 | 300 |
| 34 | Se | Selenium | 78.9718 | 4.81 | 494 | 958 | 2.55 | 1817 |
| 35 | Br | Bromine | 79.901 | 3.1028 | 265.8 | 332 | 2.96 | 1825 |
| 36 | Kr | Krypton | 83.7982 | 3.749 | 115.78 | 119.93 | 3 | 1898 |