Where Is Gold Found and Why Is It So Valuable?
Chemistry is often referred to as one central science because it combines together physics, mathematics, biology, and medical line, and the earth and environmental sciences revolving around us. Knowledge of the nature of chemicals and chemical processes that stands as the major reason for us to live on this earth, therefore, provides insights into a variety of physical and biological phenomena and makes lives easier.
First, try to read, learn and understand the underlying basic concept of the chemistry syllabus and then write down good notes with equations and important concepts which will help you revise them before exams. Break down complex tasks into smaller ones and try to research the in-depth reason for any chemical process involved. Spend a good amount of your time in the chemistry labs for you to learn the concepts with the proof before your eyes. This will make you remember the concepts as a visual effect during your exams.
Chemistry is a branch of science that is concerned with any smaller or unique substances of which a particular matter is composed and deals in-depth with the investigation and study of their properties and every reaction, and the use of such reactions to form new substances.
One can find traces of chemistry in daily life. The food we eat gives us some form of chemical reactions with the acid that is naturally produced in our stomach that helps in our digestion. The air we breathe has chemical components involved to change and breathe only oxygen for life. The cleaning chemicals used in homes or any places have some percentage of chemicals in them. Our emotions are connected with chemistry as well, oxytocin produced when we are with our loved ones is a form of a chemical reaction and literally every object we can see or touch. Some common chemistry may be obvious, but others might surprise us in unexpected forms. Our body is also made up of many unique chemical compounds, which are combinations of various elements.
Occurrence
When gold is obtained in its pure form, it is seen as a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal.
Chemical Symbol and Isotopes
Gold is a chemical element with the symbol Au derived basically from the Latin term aurum and atomic number 79, making it one of the higher atomic number elements that occur naturally.
Properties and Uses
Gold is one of the densest metals found of all other elements. It is a good conductor of heat and electricity. It is also soft and the most malleable and ductile of all the other elements and hence an ounce (28 grams) can be beaten out to 187 square feet (about 17 square meters) in extremely thin sheets called gold leaf.
More About Gold
Gold is a precious metallic element with atomic number 79 and is a part of the periodic table. Gold falls under the sixth period and group eleven in the periodic table. Gold is a transition metal. The IUPAC defines a transition metal as an element that has a partly filled subshell, or an atom that may give rise to cations despite having an incomplete subshell.
Occurrence
Gold is a naturally occurring element. It is widespread in all igneous rocks, at low concentrations. It is estimated that its abundance in Earth's crust is about 0.005 part per million. It occurs mainly in the natural state. It is usually chemically pure, except with tellurium, selenium, and bismuth. The only isotope that occurs naturally for this element is Au-197.
Gold also appears in association with deposits of copper and lead, and while the quantity present is sometimes exceedingly small, it is readily extracted as a by-product in the processing of these base metals. It is highly unusual to see large masses of gold-bearing rock rich enough to be called ores.
Two types of deposits contain a substantial amount of gold. First, the hydrothermal veins, where gold is associated with quartz and pyrite (fool's gold) and second, the deposits, which are mainly derived from the weathering of gold-bearing rocks
Chemical Symbol of Gold
The chemical symbol of gold is Au. This symbol is taken from the first two letters of the Latin name of gold: Aurum.
Gold Atomic Number
The atomic number basically determines the number of protons in the particular element. An element is identified by the number of protons, which is given by the atomic number.
The atomic number of the element Gold is 79.
Gold Electron Configuration
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An atom has various shells on which electrons revolve around the nucleus. The number of electrons present in each of the shells is known as the electronic configuration of an element.
The electronic configuration of Gold is Xe 4f145d106s1. In a simpler form, the electrons per shell of the Gold atom can be written as 2,8,18,32,18,1. Gold can have a valency between (-1) and +5, the most common being +1 and +3.
Atomic Mass of Gold
The atomic mass of an element refers to the mass of one atom of that element, which is measured in atomic mass units (u), where one atomic mass unit is equivalent to 1/12 the mass of carbon-12 isotope. When calculating the atomic mass of a particular element, we add up the mass of the protons and neutrons, because the mass of the electrons is negligible compared to their mass.
The average atomic mass for Einsteinium is 196.97. It varies depending on the isotope.
Isotopes of Gold
Isotopes are forms of an element with the same atomic numbers but different mass numbers, i.e. a different number of neutrons. Gold (Au79) has a single stable isotope, Au-197, and 36 radioisotopes, with Au-195 being the most stable with a half-life of 186 days. Gold is now known to be the heaviest mono-isotopic metal element.
Properties of Gold
Physical Properties of Gold
Gold is an amazing thermal and electrical conductor.
The element is highly resistant to corrosion and is exceptionally durable. It is not harmed by air and most of the reagents
Gold is lustrous. It is also malleable and ductile.
Gold in its purest form is extremely soft. In order to bestow strength to it, it is alloyed with another metal.
Gold appears in a slightly reddish yellow colour when available in bulk. But when finely separated, it becomes black, violet, or ruby.
Chemical Properties of Gold
The most common gold compounds are chloro-auric acid and auric chloride.
Gold is insoluble in most acids but can be dissolved in Aqua Regia (Royal Water). Aqua Regia is a mixture of hydrochloric acid and nitric acid, in which gold forms a tetrachlorocuprate anion. It also dissolves in alkaline solutions cyanide.
Gold is one of the least reactive metals, according to the reactivity series of metals. It comes just before platinum, the most non-reactive metal.
Uses of Gold
Gold is mainly used for the manufacture of jewelry, glass, and various parts in electronics. Around 75% of the world's jewelry is made using gold.
Gold may be rendered into a thread and used for embroidery.
A thin film of this metal is placed on the windows of a large building to simulate the heat of the light.
Gold is also used in medicinal products. Its radioactive isotope Au-198 is used to treat tumors in the body.
A thin layer of gold is applied to astronaut helmets to protect them from UV radiation.
FAQs on Gold in Chemistry: Symbol, Properties, and Applications
1. What is gold, and what does its chemical symbol 'Au' represent?
Gold is a precious, yellow-coloured metal known for its rarity and lustre. In chemistry, it is a chemical element with the atomic number 79. Its symbol, Au, originates from the Latin word 'aurum', which means 'shining dawn'. Gold is classified as a transition metal in the d-block of the periodic table.
2. What are the key physical and chemical properties of gold?
Gold possesses several unique properties that make it highly valuable.
- Physical Properties: It is the most malleable (can be beaten into thin sheets) and ductile (can be drawn into wires) of all metals. It is also a dense, soft metal and an excellent conductor of heat and electricity.
- Chemical Properties: Gold is a 'noble metal', meaning it is chemically unreactive. It resists corrosion, tarnishing, and attack by most acids. Its primary oxidation states are +1 (aurous) and +3 (auric).
3. Why is gold considered a 'noble metal' and why does it not rust?
Gold is called a 'noble metal' because of its remarkable resistance to chemical reactions, particularly oxidation. It does not react with oxygen in the air, which is the process that causes metals like iron to rust. This inertness is due to its stable electronic configuration and high ionisation energy, which makes it difficult for gold atoms to give up electrons and form compounds. This property ensures it retains its characteristic shine indefinitely.
4. What are the most common applications of gold in science and industry?
Beyond its primary use in jewellery and finance, gold has several critical industrial and scientific applications.
- Electronics: Its excellent conductivity and resistance to corrosion make it ideal for coating connectors, switch contacts, and wires in high-end electronics.
- Aerospace: A thin film of gold is applied to astronaut visors and satellite components to reflect infrared radiation and protect against intense solar heat.
- Dentistry: Gold alloys are used for fillings and crowns because they are non-toxic, durable, and do not wear down easily.
- Medicine: Certain gold compounds are used in treatments for conditions like rheumatoid arthritis.
5. How does the purity of gold, measured in karats, affect its properties?
The purity of gold is measured in karats (k). Pure gold is 24k, which is extremely soft and easily damaged. To increase its strength and durability for applications like jewellery, it is mixed with other metals like copper, silver, or zinc to form an alloy. For example, 18k gold contains 75% gold (18 parts out of 24) and 25% other metals. While alloying increases hardness, it slightly reduces gold's chemical inertness, making lower-karat gold more prone to tarnishing over time compared to pure 24k gold.
6. What is aqua regia and why is it one of the few substances that can dissolve gold?
Aqua regia (Latin for 'royal water') is a highly corrosive mixture of concentrated nitric acid (HNO₃) and hydrochloric acid (HCl), typically in a 1:3 molar ratio. Gold is too unreactive to be dissolved by either acid alone. However, in aqua regia, nitric acid acts as a powerful oxidising agent to form gold ions (Au³⁺), while hydrochloric acid provides chloride ions (Cl⁻) that react with the gold ions to form a stable complex ion, [AuCl₄]⁻. This second reaction removes gold ions from the solution, driving the initial oxidation forward and allowing the metal to dissolve completely.
7. How is gold different from other transition metals like iron or copper?
While gold, iron, and copper are all transition metals, gold's properties are distinctly different. The primary difference is its chemical reactivity. Iron rusts (oxidises) easily in the presence of air and moisture, and copper tarnishes to form a green patina. In contrast, gold is highly resistant to both processes. This is due to gold's stable electron structure, which makes it far less likely to engage in the chemical reactions that degrade other metals. This exceptional stability is why gold is found in its pure, native form in nature, unlike iron or copper which are typically found as ores.
