Ch.2 - Atoms & ElementsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: A historian discovers a nineteenth-century notebook in which some observations, dated 1822, were recorded on a substance thought to be a new element. Here are some of the data recorded in the notebook

Problem

A historian discovers a nineteenth-century notebook in which some observations, dated 1822, were recorded on a substance thought to be a new element. Here are some of the data recorded in the notebook: "Ductile, silver-white, metallic looking. Softer than lead. Unaffected by water. Stable in air. Melting point: 153 oC. Density: 7.3 g/cm3. Electrical conductivity: 20% that of copper. Hardness: About 1% as hard as iron. When 4.20 g of the unknown is heated in an excess of oxygen, 5.08 g of a white solid is formed. The solid could be sublimed by heating to over 800 oC." A periodic table is shown with the elements colored by era of discovery. An accessible periodic table can be found here: https://media.pearsoncmg.com/bc/bc_0media_chem/periodictable/table.html.  In Ancient times 9 elements were discovered: C, S, Fe, Cu, Ag, Sn, Au, Hg, and Pb.  In the Middle Ages to 1700 6 elements were discovered: P, Zn, As, Sb, Pt, and Bi.  From 1735 to 1843 42 elements were discovered: H, Li, Be, B, N, O, F, Na, Mg, Al, Si, Cl, K, Ca, Ti, V, Cr, Mn, Co, Ni, Se, Br, Sr, Y, Zr, Nb, Mo, Rh, Pd, Cd, Te, I, Ba, Ce, Tb, Er, Ta, W, Os, Ir, Th, U.  From 1843 to 1186 He, Sc, Ga, Ge, Rb, Ru, In, Cs, La, Pr, Nd, Sm, Gd, Dy, Ho, Tm, Yb, Tl were discovered.  From 1894 to 1918 Ne, Ar, Kr, Xe, Eu, Lu, Po, Rn, Ra, Ac, Pa were discovered. From 1923 to 1961 Tc, Pm, Hf, Re, At, Fr, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr were discovered.  And from 1965 to the present Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Cn, Uut, Fl, Uup, Lv, Uus, Uuo were discovered.

Judging from the figure, might this nineteenth-century investigator have been the first to discover a new element?