On the periodic table, we can draw a zigzag line from the element boron (symbol B) to the element polonium (symbol Po). The elements that this line passes through are the metalloids. The elements that are above and to the right of this line are the nonmetals. The rest of the elements are the metals.
Most of the properties of metals are due to the fact that the atoms in the metal do not hold onto their electrons very tightly. Each atom is separated from the others by a thin layer of valence electrons.
However, some metals are different. An example is the metal sodium. It is soft, melts at a low temperature, and is so light, it floats on water. People should not try this though, because another property of sodium is that it explodes when it touches water.
Most metals are chemically stable, and do not react easily but some do react. The reactive ones are the alkali metals like sodium (symbol Na) and the alkaline earth metals like calcium (symbol Ca). When metals do react, they often react with oxygen. The oxides of metals are basic. The oxides of nonmetals are acidic.
Compounds, which have metal atoms combined with other atoms to make molecules, are probably the most common substances on Earth. For example, common salt is a compound of sodium.
The use of metals is said to be one of the things that makes people different from animals. Before they used metals, people made tools from stones, wood, and animal bones. This is now called the Stone Age.
No-one knows when the first metal was found and used. It was probably what is called native copper, which is sometimes found in large lumps on the ground. People learned to make this into copper tools and other things, although, for a metal, it is quite soft. They learned smelting to get copper from common ores. When copper was melted over fire, people learned how to make an alloy called bronze, which is much harder and stronger than copper. People made knives and weapons from bronze. This time in human history, after about 3300 BC is often called the Bronze Age, that is, the time of bronze tools and weapons.
Around the year 1200 BC some people learned to make iron tools and weapons. These were even harder and stronger than bronze and this was an advantage in war. The time of iron tools and weapons is now called the Iron Age
Metals have been very important in human history and civilization. Iron and steel were important in the making of machines. Gold and silver were used as money in order to allow people to trade, that is, exchange goods and services over long distances.
In astronomy, a metal is any element other than hydrogen or helium. This is because these two elements (and sometimes lithium) are the only ones that form outside stars. In the sky, a spectrometer can see the signs of metals and show the astronomer the metals in a star.
In humans, some metals are essential nutrients like iron, cobalt, and zinc. Some metals can be harmless such as ruthenium, silver, and indium. Some metals can be toxic in large amounts. Other metals such as cadmium, mercury, and lead, are very poisonous. Sources of metal poisoning include mining, tailings, industrial wastes, agricultural runoff, occupational exposure, paints and treated timber.
German
German can mean different things.
When talking about a person, it can mean someone who lives in Germany, or someone who thinks of himself or herself as 'German'.
Indonesia
Indonesia, () officially the Republic of Indonesia, (Indonesian: "Republik Indonesia") is a nation in Southeast Asia. It is part of the Malay Islands. It has 18,108 islands. People live on about 6,000 of these islands. The most important islands of Indonesia are Java, Bali, Borneo, Sulawesi, and Sumatra. The capital of Indonesia is Jakarta, on Java. The president now is Joko Widodo. Modern Indonesia began on the 17th of August 1945. At 10 o'clock on that Friday morning, Sukarno read Indonesia's Declaration of Independence. Indonesia's Independence Day is a national holiday.
Indonesia is the fourth most populated country in the world with 238,452,952 people (2004 est.) Half of the population lives in Java, There are 111 people per km. The land area is 1.904 million km, or slightly smaller than Mexico. The official language of Indonesia is Bahasa Indonesia, but a total of 737 languages are spoken in different parts of Indonesia. Most of these many languages are only spoken among remote tribal groups. Other languages widely spoken in Indonesia include Javanese, Balinese and Sundanese. Indonesia's neighbors are Papua New Guinea, Malaysia, and East Timor which share land borders with Indonesia. Other nearby countries are Australia to the south, Singapore to the Northwest, and Philippines to the Northeast.
Indonesia has the most active volcanoes of any country in the world. It is also close to fault lines so there are many earthquakes and tsunamis.
Most people in Indonesia follow Islam, but Indonesia is not an Islamic country by law. Indonesia has the largest Muslim population on earth. Other religions Indonesians follow include Christianity (Protestant and Roman Catholic), Hinduism, Buddhism and Kong Hu Cu.
Indonesia has a written history as far back as the 7th century and a much longer oral history. Before the colonial Dutch came in the 1596, much of what is now Indonesia was many different kingdoms. Often they were fighting each other.
Indonesia was colonized by the Netherlands in the 17th century and renamed the Dutch East Indies. During this time, the Dutch captured thousands of Malagasy people from Madagascar and forced them to work on pepper plantations in their colonies as slaves. The Dutch treated the islands like their property until World War II.
During World War II, the Japanese drove out the Dutch and took control of Indonesia. After Japan surrendered in the war, Indonesia claimed its independence on the 17th of August 1945. The proclamation was read by Sukarno in Jakarta. Sukarno later became Indonesia's first President.
British troops came into Indonesia to restore peace and to rescue Europeans who had been prisoners of the Japanese. The British troops also had the job of shipping home 300,000 Japanese troops. The Indonesian Republicans fought the British troops, because it was expected that the British would give Indonesia back to the Dutch. The Indonesian Republicans killed many of the Japanese prisoners, before they could be sent home. They also began killing people from minority groups who might be against the new Republic. Many European and Indonesian European people were killed. Many Chinese business people and other minority groups were killed or made homeless. In Java there were many thousands of homeless people.
In 1946, the Dutch came back. When the British left in 1947, there were 55,000 Dutch soldiers in Indonesia. The Dutch action was called "Operatie Product" or "Politionele Acties". The Indonesian Republicans fought the Dutch until 1949. But the Indonesian Republicans were badly organised and often fought among themselves. As the Dutch forced the Republican soldiers out of different areas, they moved in more troops until there were 100,000 Dutch troops. The Dutch refused to obey the United Nations who said they should stop the fighting in Indonesia. The United States of America organised for meetings between Dutch and Indonesian leaders. The Dutch finally agreed to recognise Indonesia's independence in November 1949.
Because of the fighting and the bad organisation, it took a long time for the country to become peaceful, and for the economy to get better. Many Indonesian soldiers had died, between 45,000 and 100,000. Also, a very large number of civilians, Indonesians, Europeans and Chinese, had died; perhaps as many as 200,000.