- 8 Grade Jana Kaňová
HYDROGEN Let's start our tour with the element hydrogen (H). Why start with hydrogen? Hydrogen is the first element in the periodic table and the most basic and common of all elements in the Universe. Over ninety percent of all the atoms in the universe are hydrogen atoms, and they are the lightest of all elements. The name hydrogen comes from the Latin word "hydro", which means water (H2O), because water contains hydrogen atoms. Scientists use the letter "H" to represent hydrogen in chemistry. Where can we find hydrogen? The sun Hydrogen is very easy to burn. As you know, the Sun is one big ball of fire. One of the elements that make the sun burn so brightly is hydrogen. Welding and Blowtorches Sometimes you can see someone working with a blowtorch, or welding something together. They use gases that can burn very hot and make a bright flame. One of those gases is hydrogen. Plants and Sugars Hydrogen is in all plants. There are sugars all throughout plants and there is hydrogen in sugar. That's why animals eat plants- for the sugar and the energy. Cryogenics Hydrogen is used in something called cryogenics. Cryogenics is a process when scientists freeze things. When hydrogen is in a liquid form, it is very, very cold. Scientists use this cold hydrogen to freeze things very quickly. 1. Match the word with the picture: Burn Blowtorch Welding Liquid Freeze 2. True or false?
T/F Hydrogen is used to heat and freeze materials. Hydrogen is very heavy element. We can use hydrogen to weld metals together. All plants contain hydrogen. We have to be careful with hydrogen because it is easy to burn and can explode. Water contains hydrogen. THE NEXT 2 “PREPARATION QUESTIONS ARE CONNECTED TO THE LAB WORK AND PROPERTIES OF HYDROGEN” YOU DID IN THE PREVIOUS LESSON. 3. Hydrogen is prepared by reaction of 2 substances. Fill the names of these substances (reactants) in the chemical equation: ………………………… + …………………………. → hydrogen + chloride solution 4. Describe the properties of hydrogen: -state of matter (solid/liquid/gas) -color -odour (yes/no) -density (light or heavy) -typical reaction with element -typical compounds -explosiveness (can it explode?) -flammability (can it burn?)