[Chemistry Class Notes] Gold Pdf for Exam

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

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.