![]() ![]() A higher recycling rate may reduce risk to supply. The percentage of a commodity which is recycled. The number of atoms of the element per 1 million atoms of the Earth’s crust. This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores. The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems.ĭata for this section been provided by the British Geological Survey.Īn integrated supply risk index from 1 (very low risk) to 10 (very high risk). Where more than one isotope exists, the value given is the abundance weighted average.Ītoms of the same element with different numbers of neutrons. This is approximately the sum of the number of protons and neutrons in the nucleus. The mass of an atom relative to that of carbon-12. The transition of a substance directly from the solid to the gas phase without passing through a liquid phase.ĭensity is the mass of a substance that would fill 1 cm 3 at room temperature. The temperature at which the liquid–gas phase change occurs. The temperature at which the solid–liquid phase change occurs. The arrangements of electrons above the last (closed shell) noble gas. These blocks are named for the characteristic spectra they produce: sharp (s), principal (p), diffuse (d), and fundamental (f). The atomic number of each element increases by one, reading from left to right.Įlements are organised into blocks by the orbital type in which the outer electrons are found. Members of a group typically have similar properties and electron configurations in their outer shell.Ī horizontal row in the periodic table. Thunder is the sound caused by the rapidly expanding air.A vertical column in the periodic table. A bolt of lightning heats the air along its path causing it to expand rapidly. It is at this point that we see lightning and hear thunder. The connection is made and the protons rush up to meet the electrons. When this happens, a stream of negative charges pours down toward a high point where positive charges have clustered due to the pull of the thunderhead. The accumulation of electric charges must be great enough to overcome the insulating properties of the air. Lightning happens when the negative charges (electrons) in the bottom of the cloud are attracted to the positive charges (protons) in the ground. This is because light travels much faster than sound. Thunder and lightning occur at roughly the same time although you see the flash of lightning before you hear the thunder. We see it as the bright flash of a lightning bolt. This electric current is known as the return stroke. When the stepped leader and the positive charge meet, a strong electric current carries positive charge up into the cloud. The positive charges at the ground are attracted to the stepped leader, so positive charge flows upward from the ground. Once the negative charge at the bottom of the cloud gets large enough, a flow of negative charge called a stepped leader rushes toward the Earth. How Is a Lightning Bolt Formed?īecause opposites attract, the negative charge at the bottom of the storm cloud wants to link up with the ground’s positive charge. The top of the cloud becomes positively charged with particles called protons, while the base of the cloud becomes negatively charged. This separates the positive (+) and negative (-) charges of the cloud. Small negatively charged particles called electrons are knocked off some ice crystals and added to other ice crystals as they crash past each other. What's Happening Within the Cloud?Īs ice crystals high within a thunderstorm flow up and down in the turbulent air, they crash into each other. The expansion creates a shock wave that turns into a booming sound wave, known as thunder. A single stroke of lightning can heat the air around it to 30,000☌ (54,000☏)! This extreme heating causes the air to expand explosively fast. But wait a minute, what does thunder have to do with lightning? Well, lightning causes thunder. ![]() In fact it is how thunderstorms got their name. Lightning is the most spectacular element of a thunderstorm. Lightning is a very strong jolt of electricity, creating glowing gas particles called plasma that light up the night sky. ![]()
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