[CHEM CS] Chapter 7 - Periodic Table.pdf

DARRELL ER (COPYRIGHTED) © DARRELL ER (COPYRIGHTED) © TOPIC 7: PERIODIC TABLE  DARRELL ER (COPYRIGHTED) © THE ABOUT TIME CHAPTER ANALYSIS EXAM WEIGHTAGE  DARRELL ER (COPYRIGHTED) © KEY CONCEPT...

DARRELL ER (COPYRIGHTED) © DARRELL ER (COPYRIGHTED) © TOPIC 7: PERIODIC TABLE  DARRELL ER (COPYRIGHTED) © THE ABOUT TIME CHAPTER ANALYSIS EXAM WEIGHTAGE  DARRELL ER (COPYRIGHTED) © KEY CONCEPT PERIODIC TABLE ALKALI METALS HALOGENS NOBLE GASES  DARRELL ER (COPYRIGHTED) © PERIODIC TABLE Trend across a period (left to right) - Number of protons increases - Atomic radius decreases - Metallic properties decreases Trends down a group (top to bottom) Horizontal rows are known as periods. (Represent number of electron shells.) - Number of protons increases - Number of electron shells increases Vertical rows are known as groups. (Represent number of valence - Atomic radius increases electrons.) - Metallic properties remain constant The block of elements between Group II and Group III are called transition metals and they tend to have variable oxidation states.  DARRELL ER (COPYRIGHTED) © ION FORMATION PERIODIC TABLE Metallic elements will form cations as they lose their valence electrons to form positively charged ions. For example, Group I elements like Sodium (Na) will form Na+ with charge +1. Group I II III IV V VI VII VIII Valence 1 2 3 4 5 6 7 8 electro ns Period Li Be B C N O F Ne II Ion Li+ Be2+ B3+ - N3- O2- F- - Non-metallic elements will form anions as they gain Period Na Mg Al Si P S Cl Ar electrons to form negatively charged ions. III For example, Group VII elements like chlorine (CI) will form CI - with charge of –1. Ion Na+ Mg2+ Al3+ - P3- S2- Cl- -  DARRELL ER (COPYRIGHTED) © ALKALI METALS PHYSICAL PROPERTIES OF ALKALI METALS Name of element Melting points / °C Density / gcm-3 - Low melting points Lithium (Li) 180 0.534 - Low densities, lithium, sodium and potassium can float on water Sodium (Na) 98 0.971 - Good conductor of electricity & heat Potassium (K) 63 0.862 Rubidium (Rb) 39 1.532 Densities of alkali metals generally increase down the group while Caesium (Cs) 28 1.873 melting points decrease down the group. Francium (Fr) 27 - This is due to the increase in atomic radius down the group. (decreases down the (increases down the group) group) GROUP I: ALKALI METALS Chemical properties of alkali metals Group I elements are called alkali metals as they react with water to give As they have only one valence electron in their outermost shell, they alkaline solutions. form ionic compounds, with their resulting ions of +1 charge. Reactivity of alkali metals increases down the group due to the extra electron shells and the nucleus is further away, which increases Metal Chloride Nitrate Carbon Sulfate Oxide Hydroxid the ease of losing the valence electron. ate e Lithium LiCl LiNO3 Li2CO3 Li2SO4 Li2O LiOH Sodium NaCl NaNO3 Na2CO3 Na2SO4 Na2O NaOH Potassium KCl KNO3 K2CO3 K2SO4 K2O KOH  DARRELL ER (COPYRIGHTED) © HALOGENS PHYSICAL PROPERTIES OF HALOGENS - Low melting and boiling points that has an increasing trend down the group Name of element State Colour - Densities of the halogens increase down the group - Dissolve sparingly in water (chlorine, bromine and iodine) generally, but soluble in organic solvents. - Does not conduct electricity due to a lack of mobile charge carriers Fluorine (F2) Gas Pale Yellow Chlorine (Cl2) Gas Green Yellow Bromine (Br2) Liquid Reddish brown CHEMICAL PROPERTIES OF HALOGENS Iodine (I2) Solid Black Astatine (At2) Solid Black Reactivity decreases down the group. The ease of gaining a valence electron decreases as the valence shell is further away from (increases down (increasing colour intensity) the nucleus, making it more difficult to attract an electron. the group) DISPLACEMENT REACTION A more reactive halogen is able to displace a less reactive halogen GROUP VII: THE HALOGENS from an aqueous solution of its ions. Halogens usually exist as diatomic molecules. Cl2 (aq) + 2KBr (aq)  2KCl (aq) + Br2 (aq) The solution will turn reddish brown due to the aqueous bromine produced.  DARRELL ER (COPYRIGHTED) © NOBLE GAS PHYSICAL PROPERTIES OF NOBLE GASES Name of Melting points / °C Boiling points / °C State - Do not conduct electricity (lack of charge carriers) - Very low melting and boiling points element - Increasing melting and boiling points going down the group - Increasing densities of noble gases going down the group Helium (He) - -269 Gas Neon (Ne) -248 -246 Gas Argon (Ar) -189 -186 Gas USE OF NOBLE GASES Krypton (Kr) -157 -153 Gas Xenon (Xe) -111 -108 Gas Element Application Reason Radon (Rn) -71 -62 Gas Helium (He) Fill airships & hot air balloons Low density comparative (increases down the (increases down the to air group) group) GROUP 0: THE NOBLE GASES Neon (Ne) Fill interior of neon light tubes Unreactive gas All noble gases have a fully filled valence shell. Noble gases are unreactive and inert since they have a stable electronic configuration. Argon (Ar) Fill light bulbs Unreactive gas They exist as mono-atomic particles (single atoms).  DARRELL ER (COPYRIGHTED) © For more notes & learning materials, visit: IG handle: @overmugged www.overmugged.com Join our telegram channel: ‘O’ levels crash course program @overmugged Professionally designed crash course to help you get a condensed revision before your ‘O’ Levels! Need help? The 4 hour session focuses on going through key concepts and identifying commonly tested DARRELL questions! (Private tutor with 7 years of experience) Our specialist tutors will also impart valuable exam pointers and tips to help you maximise your preparation and ace your upcoming national exam! 8777 0921 (Whatsapp) The crash courses will begin in June 2021 and last till Oct 2021. @Darreller Register now on our website and secure your slots! (telegram username)