Thursday, 19 January 2017

Atoms and elements

Every material thing in the world (and probably the universe) is made from basic ingredients called elements. There are just over a hundred elements, many of which you're likely to know, such as gold, silver, lead, oxygen, hydrogen, sodium, carbon, iron, uranium and so on.

Here's a list of the main elements in some everyday things:
  • Steel is mainly iron, usually with some carbon and possibly elements such as nickel, vanadium, and chromium.
  • People are largely made of oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus (which account for about 99% of your body weight).
  • Chocolate is made of carbon, hydrogen, nitrogen and oxygen.
  • Water is oxygen and hydrogen.
  • Glass is mainly silicon and oxygen.

The physical properties of elements vary enormously. Some are gases, some are liquids. Some of the solid elements are extremely hard, and other are very soft. Some conduct electricity, others don't. Some interact violently with other elements, whereas others- like gold for example- hardly react at all. Most of them are opaque, but some transmit light (diamonds are made of carbon).

The smallest chunks of elements are called atoms. Atoms are tiny. There are about seven billion billion billion atoms in the average human body. If each atom was the size of a house brick, then a human body would be about half a million miles high.

People used to think that elements were completely unrelated from each other- that an atom of gold, say, was completely different to an atom of iron. Now we know that atoms of all elements are made of the same even-smaller building blocks, called protons and electrons. The elements only differ in the number of protons and electrons they contain. For example, hydrogen has one of each, helium has two, lithium has three, beryllium has four, boron has five, carbon has six, nitrogen has seven...every time you add another proton and another electron you get a new element.

Platinum, for instance, has seventy eight protons and seventy eight electrons. If you add another proton and another electron to an atom of platinum you get an atom of gold.

In fact, with the exception of atoms of hydrogen, all atoms have a third ingredient called a neutron, but the neutron is a bit of a distraction in our explanation of atoms, so we can leave it out for now.

NEXT LESSON: Fundamental particles

No comments:

Post a Comment