JSFiddle - React, Tailwind, and code Playground

HTML

<button id="change_color">Nemetale</button>

<table class="tabel_periodic">
  <tr>
    <td class="nemetale">
      <strong>1</strong><br>
      <acronym>H</acronym><br>
      <em>Hidrogen</em><br>
      <i>1,008</i>
    </td>
  </tr>
  <tr>
    <td class="nemetale">
      <strong>2</strong><br>
      <acronym>H</acronym><br>
      <em>Hidrogen</em><br>
      <i>2,008</i>
    </td>
  </tr>
  <tr>
    <td class="nemetale">
      <strong>3</strong><br>
      <acronym>H</acronym><br>
      <em>Hidrogen</em><br>
      <i>3,008</i>
    </td>
  </tr>
</table>

JavaScript

var trs = document.getElementsByClassName('nemetale');

document.getElementById('change_color').addEventListener('click', function(){
	for(var i=0;i<trs.length;i++){
  	changeColor(trs[i]);
  }
});

function changeColor(tr){
    tr.style.backgroundColor = 'red';
}