Answer:
Different numbers of neutrons
<span>The chemical elements</span><span> can be broadly divided into </span>metals<span>, </span>metalloids<span> and </span>nonmetals<span> according to their shared </span>physical<span> and </span>chemical properties<span>. All metals have a shiny appearance (at least when freshly polished); are good conductors of heat and electricity; form </span>alloys<span> with other metals; and have at least one </span>basic oxide<span>. Metalloids are metallic-looking brittle solids that are either </span>semiconductors<span> or exist in semiconducting forms, and have </span>amphoteric<span> or weakly </span>acidic oxides<span>. Typical nonmetals have a dull, coloured or colourless appearance; are </span>brittle<span> when solid; are poor conductors of heat and electricity; and have acidic oxides. Most or some elements in each category share a range of other properties; a few elements have properties that are either anomalous given their category, or otherwise extraordinary.</span>
