BTEC Applied Science Unit 1 Chemistry.docx

How many electrons can an s subshell hold? - correct answer 2 How many electrons can a p subshell hold? - correct answer 6 How many electrons can a d subshell hold? - correct answer 10 Which subshells are available in the first energy level? - correct answer s Which subshells are available in the second energy level? - correct answer s and p Which subshells are available in the third energy level? - correct answer s, p and d What is Hund's rule? - correct answer Orbitals must all be singly filled before they can be doubly occupied Which elements do not fill the 4s subshell before the 3d subshell? - correct answer Copper and chromium Define the term ionic bond - correct answer The electrostatic attraction between oppositely charged ions What is the charge of an ion from group 1? - correct answer +1 What is the charge of an ion from group 2? - correct answer +2 What is the charge of an ion from group 6? - correct answer -2 What is the charge of an ion from group 7? - correct answer -1 Explain how atoms of sodium react with atoms of chlorine - correct answer Na loses its 2s1 electron gaining a +ve charge. Cl gains an electron in the 3p subshell gaining a -ve charge. The opposite charges attract to form NaCl Why do ionic bonds have such high melting points? - correct answer Each +ve ion is surrounded by 6 -ve ions and vice versa. Strong electrostatic attraction in every direction. Requires a large amount of energy to break State two factors that affect the strength of an ionic bond - correct answer Size of ion and charge on ion When can ionic substances conduct electricity? - correct answer When molten or in aqueous solution Describe the properties of ionic compounds - correct answer Conduct electricity when molten or aqueous solution High melting/boiling points Usually soluble in water Define the term covalent bond - correct answer A shared pair of electrons Which metals lose electrons from the 4s subshell before the 3d subshell? - correct answer Transition metals Why do metals have such high melting points? - correct answer Strong force of attraction between positive ions and delocalised electrons. This requires a large amount of energy to overcome. State the two factors that affect the strength of metallic bonding - correct answer Size of ion Charge on ion Explain how the charge on metal ions affects the strength of the metallic bond - correct answer The larger the +ve charge the greater the attraction between the nucleus and the delocalised electrons Explain how the size of the metal ions affects the strength of the metallic bond - correct answer The smaller the +ve ion the closer the nucleus is to the delocalised electrons creating a greater attraction Explain why metals conduct electricity - correct answer The delocalised electrons 'carry' charge. Current flows because of this. Explain why metals conduct heat - correct answer Particles are paced tightly so kinetic energy is passed from ion to ion. The delocalised electrons also enable heat to be passed. Explain why metals are ductile and malleable - correct answer The lattice structure allows layers of metal ions to slide over each other without disrupting bonding Name the 3 forces between molecules - correct answer Van der Waals Permanent dipole-dipole Hydrogen bonds Order the 3 forces between molecules in order of strongest to weakest - correct answer Hydrogen bonds Permanent dipole-dipole Van der Waals How are Van der Waal's forces formed? - correct answer Electrons move to one side, caused temporary dipole. This induces a temporary dipole in neighbouring molecules. Attraction occurs between oppositely charged dipoles In what molecules do Van der Waal's forces exist? - correct answer Non-polar molecules How are permanent dipole-dipole forces formed? - correct answer Permanent dipole in one molecule attracts oppositely charged permanent dipole in neighbouring molecule In which molecules do permanent dipole-dipole forces exist? - correct answer Polar molecules Which elements must be present for hydrogen bonds to exist? - correct answer Hydrogen and either nitrogen, oxygen or fluorine What is meant by the term displacement? - correct answer When a more reactive element takes the place of a less reactive element in a compound State the equation for determining moles - correct answer Moles = mass ÷ relative atomic mass (molar mass) Define the term Avogadro's Constant - correct answer The number of atoms in a mole of a given substance. Quoted as 6.02x10^23 Define the term relative atomic mass - correct answer The average mass of an atom of an element relative to 1/12th the relative atomic mass of Carbon12 Define the term relative molecular mass - correct answer The average mass of a molecule relative to 1/12th the relative atomic mass of Carbon12 What does this number represent? 6.02x10^23 - correct answer The number of particles in a mole. Commonly called Avogadro's Constant What is the equation for calculating % yield? - correct answer % yield = (actual yield ÷ theoretical yield) x 100 What groups are included in the 's' block of the periodic table? - correct answer Groups 1 and 2 What part of the periodic table is known as the 'd' block? - correct answer Transition metals Which groups are in the 'p' block of the periodic table? - correct answer 3, 4, 5, 6 and 7 What is a group on the periodic table? - correct answer A vertical column What is a period on the periodic table? - correct answer A horizontal row Define the term first ionisation energy - correct answer The energy required to remove the outermost electron from one mole of gaseous atoms to produce one mole of gaseous +1 ions Define the term atomic radius - correct answer The distance between the nucleus of an atom and the outermost electron Define the term electronegativity - correct answer A measure of how well an atom attracts a bonding pair of electrons in a covalent bond Define the term malleability - correct answer How easily a material can be hammered into shape Define the term ductility - correct answer How easily a material can be drawn into wires Describe the trend in atomic radius down any group - correct answer Atomic radius increases Explain the trend in atomic radius down any group - correct answer Higher energy levels are filled. The orbitals in higher energy levels are further from the nucleus