Macroeconomics is about the economy in general. For example, macroeconomists study things that make a country's wealth go up and things that make millions of people lose their jobs. Microeconomics is about smaller and more specific things such as how families and households spend their money and how businesses operate.
There are a number of other branches of economics:
Famous economists in history include:
Famous economists of the 19th and 20th century include Friedrich August von Hayek, Wassily Leontief, Carl Menger, and Léon Walras.
Chemical element
A chemical element is a substance that is made up of only one type of atom, which is the smallest particle of an element. Atoms are made up of protons, neutrons, and electrons.
The number of protons in an atom is called the atomic number. For example, all atoms with 6 protons are atoms of the chemical element carbon, and all atoms with 92 protons are atoms of the element uranium. The number of neutrons in the nucleus does not have to be the same in every atom of an element. Atoms of the same element with different numbers of neutrons are called isotopes. Saying that a substance "contains only one type of atom" really means that it contains only atoms that all have the same number of protons.
The number of protons in the nucleus causes its electric charge. This fixes the number of electrons in its normal (un-ionized) state. The electrons in their atomic orbitals determine the element's various chemical properties.
Elements are the basic building blocks for all types of substances. If a substance contains more than one type of atom, it is a compound or a mixture. The smallest particle of a compound is a molecule.
118 different chemical elements are known to modern chemistry. 92 of these elements can be found in nature, and the others can only be made in laboratories. The human body is made up of 26 elements. The last natural element discovered was uranium, in 1789. The first man-made element was technetium, in 1937.
Chemical elements are commonly arranged in the periodic table. Where the elements are in the table tells us about their properties relative to the other elements.
Chemical elements are given a unique "chemical symbol". Chemical symbols are used all over the world. This means that, no matter which language is spoken, there is no confusion about what the symbol means. Chemical symbols of elements almost always come from their English or Latin names. For example, carbon has the chemical symbol 'C', and sodium has chemical symbol 'Na', after the Latin "natrium". Tungsten is called 'W' after its German name, "wolfram". 'Au' is the symbol for gold and it comes from the Latin word for gold, "aurum". Another symbol which comes from Latin is 'Ag'. This is the element silver and it comes from the Latin "argentum". Lead's symbol, 'Pb', comes from the Latin "plumbum" and the English word plumber derives from this as pipes used to be made out of lead. Some more recently discovered elements were named after famous people, like einsteinium, which was named after Albert Einstein.
Elements can join (react) to form pure compounds (such as water, salts, oxides, and organic compounds). In many cases, these compounds have a fixed composition and their own structure and properties. The properties of the compound may be very different from the elements it is made from. Sodium is a metal that burns when put into water and chlorine is a poisonous gas. When they react together they make "sodium chloride" (salt) which is generally harmless in small quantities and edible.
Some elements mix together in any proportion to form new structures. Such new structures are not compounds. They are called mixtures or, when the elements are metals, alloys.
Most elements in nature consist of atoms with different numbers of neutrons. An isotope is a form of an element with a certain number of neutrons. For example, carbon has two stable, naturally occurring isotopes: carbon-12 (6 neutrons) and carbon-13 (7 neutrons). Carbon-14 (8 neutrons) is a naturally occurring radioactive isotope of carbon. At least two isotopes of each element are known (except for Oganesson, of which only a few atoms have been made).
Elements can be classified based on physical states. At room temperature and pressure, most elements are solids, only 11 are gases and 2 are liquids.
Elements can also be classified into metals and non-metals. There are many more metals than non-metals.
However, a few elements have properties in between those of metals and non-metals. These elements are called semimetals (or metalloids).
Egypt
Egypt is a country in northeast Africa. Its capital city is Cairo. Egypt is famous for its ancient monuments, such as the Pyramids and the Sphinx.
Ancient Egypt has one of the longest histories of any country in the world as it used to be ruled by pharaohs. As a province of the Roman Empire, it became Christian and some Coptic Church people are there after more than a thousand years of Muslim rule. The Fatimid Caliphate ruled Egypt in the tenth through twelfth centuries. Mamlukes ruled it until 1798 when Napoleon defeated them. Muhammad Ali Pasha soon took over and started a dynasty of Khedives under the Ottoman Empire. The Empire fell apart after World War I. Egypt became an independent country in 1922 and the khedive became a king. Egypt is a member of the United Nations and the Arab League. It became a republic after the Army's revolution of 1952.
Egypt is a large country, but a large portion of it is desert. Most people (95% of Egypt's total people) live in areas around the coast of the Mediterranean Sea and along the Nile River. This includes the cities of Cairo, Alexandria, Aswan, and Port Said. Not many people live in the desert. Today, Egypt has about 90 million people.
Egypt is divided into 29 areas, called Governorates of Egypt.
Egypt is a country which has had many different rulers and many political systems. After World War II, Egypt was still ruled by a king, Farouk of Egypt (11 February 1920 – 18 March 1965). He was the last ruler of the Muhammad Ali dynasty.
Farouk was overthrown on 23 July 1952 by a military coup. The coup was led by Muhammad Naguib, and Gamal Abdel Nasser. From then on, Egypt had military rulers or rulers who had the backing of the army and many citizens.
Nasser became President, from 1956 to 1970. Later rulers were Anwar Sadat, and Hosni Mubarak.
Abdel Fattah el-Sisi became President in 2014.
In January 2011, thousands of protesters gathered in Cairo. They wanted Hosni Mubarak to leave office. He had been the President for almost 30 years. On February 11, 2011, Vice President Omar Suleiman made an announcement. He said that Mubarak agreed to leave office. In 2012, Egypt had a democratic election for the post of President. The winner was the Muslim Brotherhood candidate, Mohamed Morsi.
The events which followed are still controversial, but one aspect stands out. Morsi issued a declaration that in effect gave him unlimited powers. He had the power to legislate (make laws) without legal overview by the courts. This caused widespread protests. On 3 July 2013, he was unseated by a military coup council (a coup d'état). After an election in June 2014, Abdel Fattah el-Sisi became President of Egypt. Islamist movements, such as the Muslim Brotherhood, rejected the change of regime as a military coup, and not democratic.
Today, the people of Egypt are mostly Sunni Muslims. There are many Christians in Egypt today. Many of these belong to the Coptic Orthodox Church of Alexandria.
The official language in Egypt is Arabic. The majority speak Egyptian Arabic but many speak other dialects. Some Egyptians still speak Coptic and English. They also speak French and German in Egypt. These are taught in Egypt as additional languages.