Chlorides of two metals are common laboratory chemicals and both are colourless. One of the
metals reacts vigorously with water while the other reacts slowly. Place the two metals in the
appropriate block in the periodic table. justify your answer.
Answers
Answer:
1A 2A 3A 4A 5A 6A 7A 8A
(1) (2) (13) (14) (15) (16) (17) (18)
3B 4B 5B 6B 7B — 8B — 1B 2B
(3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
1 H He
2 Li Be B C N O F Ne
3 Na Mg Al Si P S Cl Ar
4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
6 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
7 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg Uub — Uuq — — — —
6 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
7 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
Group 1A (or IA) of the periodic table are the alkali metals: hydrogen (H), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These are (except for hydrogen) soft, shiny, low-melting, highly reactive metals, which tarnish when exposed to air. The name comes from the fact that when these metals or their oxides are dissolved in water, a basic (alkaline) solution results. Because the alkali metals are very reactive, they are seldom (if ever) found in their elemental form in nature, and are usually found as ionic compounds (except for hydrogen).
The alkali metals have only one valence electron in their highest-energy orbitals (ns1). In their respective periods, they are the largest elements and have the lowest ionization energies. The valence electron is easily lost, forming an ion with a 1+ charge.
The alkali metals are solids at room temperature (except for hydrogen), but have fairly low melting points: lithium melts at 181ºC, sodium at 98ºC, potassium at 63ºC, rubidium at 39ºC, and cesium at 28ºC. They are also relatively soft metals: sodium and potassium can be cut with a butter knife.
Salts of the Group 1A elements tend to be extremely soluble in water. Because the alkali metal ions are relatively large (compared to other ions from the same period), their charges densities are low, and they are easily separated from their anions and solvated by polar solvents like water.
The alkali metals (again, except for hydrogen) react vigorously with water, producing the metal hydroxide, hydrogen gas, and heat.
2M(s) + H2O(l) ® MOH(aq) + H2(g)
(Heat plus hydrogen in an oxygen atmosphere is, of course, a very dangerous combination!) The reaction becomes more vigorous as one moves from top to bottom in Group 1A: lithium sizzles fiercely in water, a small amount of sodium reacts even more vigorously, and even a small amount of potassium metal reacts violently and usually ignites the hydrogen gas; rubidium and cesium explode. This is a result of the fact that the size of the element increases as we move down the group: as the size of the metal increases, the valence electron is farther away from the nucleus, and is thus more easily removed (i.e., the ionization energy is lower).
Hydrogen (H, Z=1).
Although hydrogen is placed at the top of Group 1A in most versions of the periodic table, it is very different from the other members of the alkali metal group. In its elemental form, hydrogen is a colorless, odorless, extremely flammable gas at room temperature, consisting of diatomic molecules of H2. Molecular hydrogen boils at -253°C (20 K), and freezes at -259°C (14 K). Under tremendous pressure (about 2 million atmospheres), it can be converted to a metallic form, capable of conducting electricity. (It has been theorized that center of the planet Jupiter consists of metallic hydrogen.) In the Earth's crust, it is found at a concentration of 1500 ppm (mostly in the form water and of organic compounds), making it the 10th most abundant element.
Hydrogen is the most abundant element in the universe (75% by weight, or 88% of all of the atoms of the universe); hydrogen and helium together make up 99% of the "normal" matter of the universe. (Of course, there's also "dark matter" and "dark energy" to worry about, but that's another story.) Hydrogen, helium, and trace amounts of lithium were produced at the beginning of the Universe in the Big Bang, and became concentrated into stars by the force of gravity. The fusion of hydrogen to form helium provides the power that makes stars shine: in the Sun, 600 millions tons of hydrogen undergo fusion to form helium every second, converting 5 million tons of matter into energy (Einstein's good ol' E = mc2). The fusion of hydrogen and its isotopes (see below) also powers the hydrogen bomb, which contains lithium deuteride (LiD) and tritium; the explosion of a fission-powered bomb produces neutrons which initiate fusion of the deuterium with the tritium, releasing vast amounts of energy. Research into achieving controlled nuclear fusion to generate electricity is being conducted, but the extremely high temperatures that are necessary to initiate the fusion reactions present a major challenge to physicists.
Explanation:
Mark as brainlist please