When two magnets are brought near each other, like poles repel; opposite poles attract. When a magnet is brought near a piece of iron, the iron also gets attracted to the magnet, and it acquires the same ability to attract other pieces of iron.
Answer:
Threatened Species: A threatened species is a species at risk but not yet endangered. California sea otters were classififed as a threatened species. Laws were passed to protect the otters and now they have increased their population size.
Invasive Species: One of the main causes of extinction and endangered species is the introduction of an exotic species. New exotic species are called invasive species. Invasive species can disrupt food chains, carry disease, prey on native species directly, and out-compete native species for limited resources, like food.
Extinction: If a population decreases too much in numbers, they disappear. Extinct species mean that the species has died out and no individuals left. An example of extinction: New Zealand was once home to a bird called the Giant Moa. Humans settled as their population increased the Moa population decreased. The species is now extinct.
Explanation:
Fusion occurs constantly on our sun, which produces most of its energy via the nuclear fusion of hydrogen into helium. Neither do fusion reactions produce the large amounts of dangerous radioactive waste that fission reactions do. That's why it's such a dreamy source of energy.
Answer: Elements in Group 2
Explanation: The periodic table was arranged by Dmitri Mendeleev specifically around similarites in their chemical behaviors. He found that as atomic number increases, at some point an element starts to react in a manner similar to a previous one. When that happened, he would place the larger element under the smaller one, and eventually noticed a periodicity in the table. Elements in a column (Groups) had similiar chemical properties. We know today that these similarities are due to the electron configuration, and that these configurations repeat themselves. He left gaps in the table when he could find an existing element with properties similar to others in that group. I big leap of faith, but it worked. Elements for those missing boxes were eventually discovered.
