Non-Metals

Announcements The quiz has been delayed due to the ERB tests and we will have in next Tuesday. The next quiz on metals will be shortly after (with in a few days) Poster deadline is 22nd April Previous question: How would you expect the reactivity to be for sodium vs. caesium?

Goal of the class To introduce and discuss the different types of nonmetals Question of the day: How are the different types of non metals categorized? Previous Answer: stability can be predicted based on the size of the atoms. Previous question: How could the stability of an atom be predicted?

Non-Metals The elements of the periodic table marked in red are non-metals. Same as before

Non-Metals Nonmetals can be broken into different categories Polyatomic Diatomic Monatomic Can be very reactive or completely unreactive Solid, liquid or gas Poly means many Dia = 2 Mono = 1

Noble Gases Group 8 (0) of the periodic table are called the noble gases. They were once called the inert gases but that name was changed. Monatomic nonmetal Highly unreactive Full outer shell of electrons Same as before

Properties of Noble Gases Odourless Colourless Very low melting and boiling temperatures All gases at room temperature High ionization energy Same as before

Properties of Noble Gases Reminder from our section on electron orbits, the magic numbers are 2, 8, 8. helium 2 neon 2,8 Same as before argon 2,8,8

Noble Gases Helium is less dense than air, so it’s great for all kinds of balloons. Helium balloons lift instruments into the upper atmosphere to measure atmospheric conditions. they are good conductors of heat and electricity they can be hammered or bent into shape easily

Noble Gases Hydrogen is less dense than helium and used to be used. However, hydrogen is highly flammable and is not used anymore. they are good conductors of heat and electricity they can be hammered or bent into shape easily

Noble Gases Each noble gas produces a unique color. Helium glows yellow, neon glows red-orange, and argon produces a bluish-violet color. The “neon” lights you see in advertising signs can contain any of the noble gases, not just neon. Electricity is passed through the glass tubes that make up the sign.

Noble Gases Argon is the most abundant noble gas found on earth and makes up about 1% of the atmosphere. HeNe laser Many noble gases are used in high powered lasers

Halogens The elements in group 7 of the periodic table, on the right, are called the halogens. I Br Cl F At fluorine chlorine they are good conductors of heat and electricity they can be hammered or bent into shape easily bromine iodine astatine

Halogens Halogens are very reactive non metals. They are all toxic or harmful because they are so reactive. Before antiseptics, iodine was used to clean wounds as it is harmful to all things, including bacteria. Chlorine, bromine, Iodine

Halogens They are also never found free in nature because of their reactivity – they are found as compounds with metals. These halogen-metal compounds are salts, which give halogens their name – ‘halo-gen’ means ‘salt-former’. Talk about ions formed Na+, Li+, K+ etc

Halogens All halogens have seven electrons in their outer shell. This means that: They can easily obtain a full outer shell by gaining one electron. They all gain an electron in reactions to form negative ions with a -1 charge. They have similar chemical properties. fluorine 2,7 chlorine 2,8,7 Talk about ions formed Na+, Li+, K+ etc bromine 2,8,8,7

Uses Fluorine is added to toothpaste to prevent tooth decay Chlorine is added to the water in swimming pools as a disinfectant or some bleaches. Conductivity is both thermal and electrical

Homework Revise for quiz! http://phet.colorado.edu/en/simulation/build-an-atom