Gold as everyone knows is a noble metal sought after by everyone. By being noble means it is resistant to chemical reactions like corrosion by air and water combination.
The answer tothe question why it has the colour it has lies in electronic configuration of gold atoms. Its electronic configuration is [Xe] 4f14 5d10 6s1 where Xe stands for Xenon. The outermost orbitals are 5d and 6s. There is one electron in the outermost shell. In the geometric structure, atoms are arranged in a particular config And the lone electrons present the 6s orbitals are diffused in the lattice which means that individual electron in a atom has lost the address of parent atom and now belong to the community of gold atoms.
How do the objects we see have different colours? Colours are hidden in white light emanating from the sun. The visible spectrum of light components is composite of 7 colours remembered using “VIBGYOR” where V is for violet and has the maximum energy in the visible spectrum and R is for red with lowest energy.
When it falls on an object, the object absorbs some fraction of the light and reflects the rest of it. Which color or colors wavelengths it will absorb depends upon the unique structure of the object molecules. We see the resultant of colours which are reflected.
In case of gold, the energy difference between the 5d and 6s levels is 2.7 electron volts. The blue light has exactly this energy in its photon packets. So when light falls on it, it completely absorbs the blue fraction of the light. The remains reflected resultant light is exactly the colour which is that of gold.
Human beings are endowed with power of thinking. All this is possible due to highly evolved brain. But some of us humans are exceptional. Do they see visions? They can predict the events of future. Following are such incidences from the science field.
Sir P.A.M Dirac is considered as the greatest physicist in Britain after Newton. A stern father made him the man of few words. But this trait turned on an intense internal energy which manifested in the form of beautiful equations when he married Einstein’s relativity with quantum mechanism. On the basis of his research, he envisaged sub atomic particles which have equal and opposite electrical charge and equal mass to particles like electrons. His equations yielded two solutions like quadratic equations. Proof came soon when in a experiment in cloud chamber, a particle, hitherto, unknown was observed following mirror trajectory to the electrons emitted from a radioactive particle. It is clear that in a magnetic field, the particles follow a circular trajectory. So this particle was opposite of electron with equal mass. So his prediction was borne true. This particle is called anti-electron or positron. Soon, it became known that there is antimatter to every type of matter. In fact, now scientists believe that there exist space with antimatter and efforts are on to exploit their potential.
Another such great person was a Russian chemist. His name was Dmitri Ivanovich Mendeleev. At the time when he was on the scene, the concept of atomic number of elements was unknown. Only few elements were known to chemists. The physical parameter which was considered important for distinguishing the elements from each other was atomic weight. He was the first man to arrange the elements in groups based on their properties. His insight of the nature was so great that he left many blank places for elements which were not known then. He gave them names prefixed by eka, dvi and tri added to the element preceding the one with eka prefix. For example, ekaboron was the name of element which occupied next place to Boron. It was later discovered and is called Scandium. He had predicted all the properties of the element to be discovered and they matched almost exactly to the element when discovered. His periodic table is the forerunner of the modern periodic table which has evolved over time and is based on the atomic number concept. It is based on the premise that elements in a group have similar electronic configuration and all the elements fall in periods with elements in group having similar properties but increasing atomic numbers. Each element has an added shell of electrons to the previous one. Incidentally, prefixes eka, dvi and tri have been adapted from Sanskrit and mean one, two and three. This love for Sanskrit is said to be due to the influence from a friend who was a Sanskrit scholar.
Kekule, an organic chemist was another exception. He dreamed dreams about atoms and their arrangement. He did it another way around. To explain the unusual properties of a chemical compound and its strange molecular weight, he was so much involved in the thoughts that he was always lost in the reverie. Even while travelling in bus from his laboratory to his home he was so absorbed in the thoughts of figuring out the formula that will explain the observed properties that he had to be reminded by the conductor about the end of his journey. And one day, he saw a dream in which atoms were dancing. Then heavier of them turned into snakes which were joined to each other as each snake has the tail of other one in his mouth. He woke up and rest of night worked out the formula of the first of the aromatic compounds called Benzene.