The nobles of Spain no longer had to fight anyone since the internal feuds were over. No one could challenge their power. In many ways it was held together as a reign of terror. People who challenged them were often called heretics, so that the Inquisition could torture them, and then nobles take the property.
For ordinary people on both sides of the Atlantic Ocean, life got worse. A few rulers got rich. Today we would say that these people were guilty of war crimes, genocide and crimes against humanity. Many Church people who had the power to speak out at that time, did so, and they said many of the same things as we would say today. But none of this mattered much to the rulers.
The great satire Don Quixote was written about this time.
In the 18th century, there was doubt over who should become king of Spain; this doubt led many of the kings of Europe to fight to become king of Spain. This was called the War of the Spanish Succession.
France occupied Spain for a long time. This made Spain very weak. It also made Spain lose its empire in North and South America; all of the parts of that empire became their own countries, or were taken over by other countries such as the United States of America.
There was not much peace in Spain during the first part of the 20th century. Some Spaniards tried to set up a government chosen by the people (a democracy), and they made the King of Spain leave the country. However, in 1936, two different groups of Spaniards went to war over whether the government should be a democracy, or take orders from one person. In 1939, those who wanted democracy were defeated, and a dictator named Francisco Franco took over the government.
Franco died in 1975. He had decided that Spain should have a king again, and he chose Juan Carlos, the grandson of the king who had been forced to leave the country, to be king. But the king did not rule as a dictator; instead, he chose to set up a democracy. Also since Franco's death, Spain appointed Adolfo Suárez to became Spain's first democratically elected prime minister. Now Spain is a modern democratic country, and does business with many countries around the world. It is a part of the European Union.
Height
Height is the distance between the lowest end and highest end of an object.
For example, people consider the bottom of the foot a person's lowest end, and the top of the head a person's highest end. If the distance between the bottom of a person's foot and the top of that person's head is 64 inches, then that person's height is 64 inches.
Historian
A historian is someone who studies history. Historian use written sources to understand past events and societies.
Human body
The human body is the body of a person. It is the physical structure of a person.
The body is a thing that can be hurt or killed. Its functions are stopped by death. You need your muscles and your joints to move.
Some people study the human body. They look at where it is different from or the same as other animals' bodies. These animals can be alive today. Or they can be extinct animals like other hominids. (Hominids are primates that are close to humans. Neanderthals and "Homo erectus" were hominids.) Some people study how the human body works and lives in its environment. Some people study what people think about their body. Artists study how to draw or paint the human body.
Many different fields of study look at the human:
Various organ systems give the body the ability to live and do things.
The human body is like other animals. The skeleton, muscles and other parts are very much like those of other primates. Our body is also like other mammals, and somewhat like other vertebrates. DNA differences follow a similar pattern. The human genome is closer to that of other primates than to other vertebrates, and closest to chimpanzee.
Hydrogen
Hydrogen is a chemical element. It has the symbol H and atomic number 1. It has a standard atomic weight of 1.008, meaning it is the lightest element in the periodic table.
Hydrogen is the most common chemical element in the Universe, making up 75% of all normal (baryonic) matter (by mass). Most stars are mostly hydrogen. Hydrogen's most common isotope has one proton with one electron orbiting around it.
Hydrogen is classed as a reactive nonmetal, unlike the other elements appearing in the first column of the periodic table, which are classed alkali metals. The solid form of hydrogen is expected to behave like a metal, however.
When alone, hydrogen usually binds with itself to make dihydrogen (H) which is very stable, due to its high bond dissociation energy of 435.7 kJ/mol. At standard temperature and pressure, this hydrogen gas (H) has no colour, smell or taste. It is not toxic. It is a nonmetal and burns very easily.
Molecular hydrogen is flammable and reacts with oxygen:
2 H(g) + O(g) → 2 HO(l) + 572 kJ (286 kJ/mol)
At temperatures above 500 degrees Celsius, hydrogen spontaneously ignites in air.
While hydrogen gas in its pure form is not reactive, it does form compounds with many elements, particularly halogens, which are very electronegative. Hydrogen also forms vast arrays with carbon atoms, forming hydrocarbons. The study of the properties of hydrocarbons are known as organic chemistry.
The H anion (negatively charged atom) is called a hydride, although the term is not widely used. An example of a hydride is lithium hydride (LiH), which is used as a "spark plug" in nuclear weapons.
Acids dissolved in water typically contain high levels of hydrogen ions, in other words, free protons. The level of them is usually used to determine its pH, which basically means the content of hydrogen ions in a particular volume. For example, hydrochloric acid, found in people's stomachs, can dissociate into a chloride anion and a free proton, and the property of the free proton is how it can digest food by corroding it.
Although rare on Earth, the H cation is one of the most common ions in the universe.
Hydrogen has 7 known isotopes, two of which are stable (H and H), which are commonly referred to protium and deuterium. The isotope H is known as tritium and has a half life of 12.33 years, and is produced in small amounts by cosmic rays. The remaining 4 isotopes have half lives on the scale of yoctoseconds.
In its pure form on Earth, hydrogen is usually a gas. Hydrogen is also one of the parts that make up a water molecule. Hydrogen is important because it is the fuel that powers the Sun and other stars.
Hydrogen makes up about 74% of the entire universe. Hydrogen's symbol on the Periodic Table of Elements is H.
Pure hydrogen is normally made of two hydrogen atoms connected together. Scientists call these diatomic molecules. Hydrogen will have a chemical reaction when mixed with most other elements. It has no color or smell.
Pure hydrogen is very uncommon in the Earth's atmosphere, because nearly all primordial hydrogen would have escaped into space due to its weight. In nature, it is usually in water. Hydrogen is also in all living things, as a part of the organic compounds that living things are made of. In addition, hydrogen atoms can combine with carbon atoms to form hydrocarbons. Petroleum and other fossil fuels are made of these hydrocarbons and commonly used to create energy for human use.
Some other facts about hydrogen:
Hydrogen was first separated in 1671 by Robert Boyle. Henry Cavendish in 1776 identified it as a distinct element and discovered that burning it made water.
Antoine Lavoisier gave Hydrogen its name, from the Greek word for water, 'υδορ (pronounced /HEEW-dor/) and gennen meaning to "generate" as it forms water in a chemical reaction with oxygen.
The main uses are in the petroleum industry and in making ammonia by the Haber process. Some is used elsewhere in the chemical industry. A little of it is used as fuel, for example in rockets for spacecraft. Most of the hydrogen that people use comes from a chemical reaction between natural gas and steam.