Across 4 A heavy ductile magnetic metallic element; is silver-white in pure form but readily rusts; used in construction and tools and armament; plays a role in the transport of oxygen by the blood; Metal shackles; for hands or legs (4) 6 A hard ferromagnetic silver-white bivalent or trivalent metallic element; a trace element in plant and animal nutrition (6) 8 A colourless and odourless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere (5) 10 A solid silvery grey radioactive transuranic element whose atoms can be split when bombarded with neutrons; found in minute quantities in uranium ores but is usually synthesized in nuclear reactors; 13 isotopes are known with the most important being plutonium 239 (9) 11 A bluish-white lustrous metallic element; brittle at ordinary temperatures but malleable when heated; used in a wide variety of alloys and in galvanizing iron; it occurs as zinc sulphide in zinc blende (4) 12 A soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia (4) 15 A highly unstable radioactive element (the heaviest of the halogen series); a decay product of uranium and thorium (8) 17 A soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull grey. Mixture of graphite with clay in different degrees of hardness; the marking substance in a pencil (4) 18 A radioactive transuranic metallic element; discovered by bombarding uranium with helium atoms (9)

19 A hard brittle blue-grey or blue- black metallic element that is one of the platinum metals; the heaviest metal known (6) 20 A soft bluish-white ductile malleable toxic bivalent metallic element; occurs in association with zinc ores (7) 21 A heavy brittle metallic element of the platinum group; used in alloys; occurs in natural alloys with platinum or osmium (7) 22 A rare soft silvery metallic element; occurs in small quantities in sphalerite (6) Down 1 A hard malleable ductile silvery metallic element that is resistant to corrosion; used in alloys; occurs in pentlandite and smaltite and garnierite and millerite. A United States coin worth one twentieth of a dollar (6) 2 A soft yellowish-white trivalent metallic element of the rare earth group; can be recovered from bastnasite or monazite by an ion- exchange process (12) 3 A light strong grey lustrous corrosion-resistant metallic element used in strong light- weight alloys (as for aeroplane parts); the main sources are rutile and ilmenite (8) 5 A colourless odourless gaseous element that give a red glow in a vacuum tube; one of the six inert gasses; occurs in the air in small amounts (4) 7 A light strong brittle grey toxic bivalent metallic element (9) 9 A white soft metallic element that tarnishes readily; occurs in rare earth minerals and is usually classified as a rare earth (9) 10 A light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite (9) 13 A heavy precious metallic element; grey-white and resistant to corroding; occurs in some nickel and copper ores and is also found native in some deposits (8) 14 A silvery ductile metallic element found primarily in bauxite (8) 16 A bivalent and trivalent metallic element of the rare earth group (8)