Answer the following questions. 1. What is the atomic number of oxygen?

1. What is the atomic number of oxygen? 2. How much oxygen is there in the air we breathe? 3. What does the oxygen cycle involve? 4. Photo-synthesis is a process that converts carbon dioxide into organic compounds using sunlight, isn’t it? 5. How many oxygen atoms does ozone combine? 6. From what countries were the scientists who researched, documented and helped discover oxygen?

2. Put down the following words into 2 lists: a) Nouns, b) Adjectives. Underline the word-forming siffixes. Add the lists with nouns and adjectives of your own with the same suffixes.

Various, oxidizer, industrial, dangerous, treatment, application, scientific, medical, plastic, patient, pharmacist, harmful, different, pollutant, movement, essential, tasteless, pressure, condition, reactive.

4. Helium

to float	плисти	buoyant	плавучий, здатний триматися на поверхні
noble	благородний	to leak	витікати
jointly	спільно	hoax	містифікація, трюк
to replenish	поповнювати	to inhale	вдихати
a blimp	дирижабль	to choke	задихатися, душити

Helium is lighter than the air around us so it floats, that’s why it is perfect for the balloons you get at parties. Helium is a chemical element with the symbol He and atomic number 2. It is a colorless, tasteless and odorless gas. Helium is the second most common element in the Universe (after hydrogen), making up around 24% of its mass.

Helium is part of a group of chemical elements called noble gases; the other five that occur naturally are neon, argon, krypton, xenon and radon. Under normal conditions they share similar properties, including being less likely to participate in chemical reactions due to their outer shell of electrons being full. Helium is the second least reactive element after neon.

French and English astronomers Pierre Janssen and Norman Lockyer are jointly credited with discovering helium after spectral analysis of sunlight following a solar eclipse in 1868.

The word helium comes from the Greek word meaning sun (helios). It was named by Lockyer and English chemist Edward Frankland.

The USA is the world’s largest supplier of helium, with many reserves found in large natural gas fields.

The rate at which helium is currently being used by humans is much faster than the rate at which the reserves are being replenished. New technologies for obtaining or recycling helium are one way for gas companies to help slow this problem.

Because helium is lighter than air it is commonly used to fill airships, blimps and balloons. As it doesn’t burn or react with other chemicals, helium is relatively safe to use for this purpose. While hydrogen is 7% more buoyant than helium it has a much higher fire risk.

You might have noticed the helium balloon you got from the amusement park slowly falling to the ground after a few days, this happens as the helium gradually leaks from the balloon. Helium has a lifting force of around one gram per liter. A balloon that holds 10 liters of helium should therefore lift an object weighing 10 grams. Unfortunately you’ll need around 5,000 of these balloons if you weigh around 50kgs and want to get off the ground.

Because helium is less dense than normal air, when inhaled from a source such as a helium balloon, it briefly changes the sound of a person’s voice, making it sound much higher. However, breathing in too much helium can be very dangerous, potentially choking people due to a lack of oxygen.

Helium can be in a liquid and even solid state but they can only occur at temperatures near absolute zero. Liquid helium is used to cool metals for superconductivity use. The European Organization for Nuclear Research’s (CERN) Large Hadron Collider uses liquid helium to maintain an extremely low temperature.

Helium is often used in space programs, displacing fuel in storage tanks and having other rocket fuel applications.

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