Period 1 element facts for kids

A period 1 element is a chemical element found in the first row, or period, of the periodic table. The periodic table organizes all known elements. It shows how their properties change and repeat. Elements in the same row have different properties as their atomic number increases. A new row starts when chemical properties begin to repeat. This means elements in the same column, or group, have similar properties.

The first period is special because it has fewer elements than any other period. There are only two elements in this first row: hydrogen and helium. This happens because of how atoms are built. In the first energy level of an atom, there's only room for two electrons. Once these two spots are filled, a new period begins. This is sometimes called the "duet rule" because these elements only need two electrons to have a full outer shell.

Unique Elements in Period 1

Even though both hydrogen and helium are in the s-block of the periodic table, they don't act like other s-block elements. Scientists sometimes debate where exactly to place them in the periodic table because they are so unique.

Hydrogen's Special Spot

Hydrogen is a very unique element. Its position on the periodic table can be tricky. Sometimes it's placed above lithium, sometimes above carbon, or even above fluorine. Some tables show it in two places, or even floating above all other elements. This is because hydrogen can act like different types of elements depending on the situation.

Helium's Place

Helium is almost always placed above neon. This is because helium is a noble gas, just like neon. Noble gases are very stable and don't easily react with other elements. Sometimes, though, helium is shown above beryllium because their electron arrangements are similar.

Elements in the First Period

All About Hydrogen

Hydrogen discharge tube

Deuterium discharge tube

Hydrogen (symbol: H) is a chemical element with an atomic number of 1. At normal room temperature and pressure, hydrogen is a gas that has no color, no smell, and no taste. It is a nonmetal and is very flammable. Hydrogen usually exists as a diatomic gas, meaning two hydrogen atoms join together to form H₂. It is the lightest element, with an atomic mass of about 1.008 amu.

Hydrogen is the most common element in the universe. About 75% of all elements in the universe are hydrogen. Stars like our Sun are mostly made of hydrogen in a super hot, charged state called plasma. On Earth, hydrogen is less common as a pure element. We usually produce it from other substances like natural gas.

Hydrogen is used in many ways. It helps to make ammonia, which is used in fertilizers. It's also used in oil refineries to improve fuels. We can also make hydrogen from water using a process called electrolysis. However, this is usually more expensive than making it from natural gas.

The most common type of hydrogen is called protium. It has one proton and no neutrons. Hydrogen can form compounds with almost all other elements. It is a key part of water (H₂O) and most organic compounds. It is also very important in how acids and bases react.

All About Helium

Helium discharge tube

Helium (symbol: He) is a colorless, odorless, tasteless, and safe inert monatomic gas. It is the second element in the noble gas group on the periodic table, and its atomic number is 2. Helium has the lowest boiling and melting points of all elements. It only exists as a gas unless it's under extreme conditions.

Helium was first found in 1868 by a French astronomer named Pierre Janssen. He saw a strange yellow line in the light from a solar eclipse. Later, in 1903, large amounts of helium were found in natural gas fields in the United States. The U.S. is still the biggest supplier of helium today.

Helium has many uses. It's used in cryogenics (very cold temperatures) and to cool superconducting magnets. It's also used in deep-sea diving systems. You might know it best for inflating balloons and airships. In industry, it's used as a protective gas for things like arc welding. If you inhale a small amount of helium, it temporarily changes the sound of your voice!

Helium is the second lightest element and the second most common element in the universe. Most helium was formed during the Big Bang. New helium is also made inside stars when hydrogen atoms join together in nuclear fusion. On Earth, helium is rare. It's created when some radioactive elements naturally break down. This helium gets trapped with natural gas and is then separated for use.

Images for kids

• 

  Hydrogen's electron configuration is 1.

• 

  Helium's electron configuration is 2.

See also

In Spanish: Elementos del periodo 1 para niños