Four eons characterize Earth’s history; from oldest to youngest, these are the Hadeon, Archean, Proterozoic, and Phanerozoic. Collectively, the Hadean, Archean, and Proterozoic are sometimes informally referred to as the “Precambrian.” (The Cambrian period defines the beginning of the Phanerozoic eon; so, all rocks older than the Cambrian are Precambrian in age.)
We live in the Phanerozoic, which means visible life.
.When the solar system settled into its current layout about 4.5 billion years ago, Earth formed when gravity pulled swirling gas and dust to become the third planet from the Sun. Like its fellow terrestrial planets, Earth has a central core, a rocky mantle, and a solid crust. Early in its evolution, Earth suffered an impact by a large body that catapulted pieces of the young planet’s mantle into space. Gravity caused many of these pieces to draw together and form the moon, which orbits around its creator. The moon settled the earth down.
Earth’s core pushed rocks and minerals up, all the way to the surface. Magma can push through holes or cracks in the crust, causing a volcanic eruption. When magma flows or erupts onto Earth’s surface, it is called lava. Like solid rock, magma is a mixture of minerals. It also contains small amounts of dissolved gases such as water vapor, carbon dioxide, and sulfur. Oceans of Magna covered the surface of the earth.
Magma can rise when pieces of Earth’s crust called tectonic plates slowly move away from each other. Magma also rises when these tectonic plates move toward each other. When this happens, part of Earth’s crust can be forced deep into its interior. The high heat and pressure cause the crust to melt and rise as magma. The four standard Planet Surface Processes are Cratering, Volcanoes, Erosion, and Weathering (chemical and physical). A basalt crust floats on a magma ocean.
DOING THE BUILD-OUTS:
Chemical bonds are forces that hold atoms together to make compounds or molecules.
Chemical bonding, the three basic types are: covalent, ionic, and metallic. An ionic bond is formed when valence electrons are transferred from one atom to the other to complete the outer electron shell. Chemical bonding: Any of the interactions that account for the association of particles into molecules, ions, crystals, and other stable species that make up the familiar substances of the everyday world. A covalent bond is the strongest bond. The weakest of the intramolecular bonds or chemical bonds is the ionic bond. An Ionic bond is also called an electrovalent bond.
An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. It is an oxidizing agent that, by its accepting electrons, it is reduced in the process.
Electron acceptors are ions or molecules that act as oxidizing agents in chemical reactions. Electron donors are ions or molecules that donate electrons and are reducing agents. … Oxygen is an oxidizing agent (electron acceptor), and hydrogen is a reducing agent (electron donor).
An atom is composed of two regions: the nucleus, which is in the center of the atom and contains protons and neutrons, and the outer region of the bit, which holds its electrons in orbit around the nucleus.
Electron shuffling: The electrons move from negatively charged parts to positively charged ones.
An atom that gains or loses an electron becomes an ion. When an atom loses all of its electrons, it becomes completely ionized. With its extra packet of energy, the electron becomes excited, promptly moves out of its lower energy level, and takes up a position in a higher energy level. Almost immediately, the excited electron gives up the extra energy it holds, usually in the form of light, and falls back down to the lower energy level again. Helium compounds are best understood as donor-acceptor molecules consisting of He as electron donor and the respective acceptor fragment.
