Suppose we have an article with a title and several paragraphs: There is only one stable form of cesium naturally present in the environment,133Cs (read as cesium one-thirty-three). Naturally occurring cesium is not radioactive and is referred to as stable cesium.
It is defined in the CSS Selectors Level 3 spec as a “structural pseudo-class”, meaning it is used to style content based on its relationship with parent and sibling content. Cesium is a naturally occurring element found combined with other elements in rocks, soil, and dust in low amounts. Teachers love demonstrating the principle of reactivity by dropping an alkali metal in water only for the class to watch in awe as it spews fire and explodes.The :first-of-type selector in CSS allows you to target the first occurence of an element within its container. Francium, which is very rare, doesn't have many commercial applications but is used in research and to diagnose some forms of cancer.įinally, all the alkali metals are also incredibly useful teaching tools in the field of chemistry. Rubidium is used in medical imaging and vacuum tubes. Cesium is used in atomic clocks, drilling and in creating optical glass among other highly specialized applications. The more reactive elements, cesium, rubidium and francium, have fewer natural uses.
Lithium is used in battery production, and lithium salts are used as a mood-stabilizing drug. Potassium nitrate (saltpeter) was used to make gunpowder and, incidentally, is an excellent food preservative, responsible for giving hot dogs and other processed meats their pink hue. Potassium hydroxide is used in soap solutions. Potassium salts (potassium chloride) can be used to treat low blood potassium and are an important ingredient in commercial fertilizer. "As you go down the periodic table, the alkali metals become more inclined to lose their valence electron" and thus, "the amount of the element found in nature also decreases, later discovery dates." "All of these elements were first discovered in compounds some of the discoveries are hard to attribute due to the abundance and usage of the compounds," says Nataro. If an element is highly reactive, it's harder to find its pure form in nature. For example, sodium chloride (table salt) and sodium carbonate (soda ash) are widely available sodium compounds. Since alkali metals react readily, they are usually found in conjunction with other metals in nature. So, all of the alkali metals like to make cations that have a charge of +1." Alkali Metals in Nature It also includes history, demos, patterns, and a browser support chart. This complete guide explains everything about flexbox, focusing on all the different possible properties for the parent element (the flex container) and the child elements (the flex items). When this happens, the atom is referred to as an ion and since it would have a positive charge, it is called a cation. Our comprehensive guide to CSS flexbox layout. "As electrons have a charge of -1, losing an electron causes the atom to have a charge of +1. Chip Nataro, chemistry professor at Lafayette College in Easton, Pennsylvania. All of the alkali metals like to give up their single valence electron," says Dr. In this process, the alkali metal is said to be oxidized, and whatever takes the electron from the alkali metal is reduced. "Since the alkali metals only have one valence electron, they typically achieve this state by giving up that electron. That's why chemists talk about atoms wanting to achieve a "noble gas configuration." Noble gases (elements like neon and helium) are not very reactive because their outermost electron shells are full. In fact, reactivity in chemistry is defined by the number of electrons in the outermost shell. Having only one valence electron in the outermost shell makes it very easy for the alkali metal atoms to reach points of stability - they just need to lose one electron! This willingness and ease of losing an electron to reach a state of equilibrium is known as high reactivity.
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