alkaline earth metals

reactivity of alkaline earth metals

All alkaline Earth metals have similar properties because they all have two valence electrons. They readily give up their two valence electrons to achieve a full outer energy level, which is the most stable arrangement of electrons. As a result, they are very reactive, although not quite as reactive as the alkali metals in group 1. For example, alkaline Earth metals will react with cold water, but not explosively as alkali metals do. Because of their reactivity, alkaline Earth metals never exist as pure substances in nature. Instead, they are always found combined with other elements. The reactivity of alkaline Earth metals increases from the top to the bottom of the group. Thats because the atoms get bigger from the top to the bottom, so the valence electrons are farther from the nucleus. When valence electrons are farther from the nucleus, they are attracted less strongly by the nucleus and more easily removed from the atom. This makes the atom more reactive. Q: Alkali metals have just one valence electron. Why are alkaline Earth metals less reactive than alkali metals? A: It takes more energy to remove two valence electrons from an atom than one valence electron. This makes alkaline Earth metals with their two valence electrons less reactive than alkali metals with their one valence electron.

the second group

Barium (Ba) is one of six elements in group 2 of the periodic table, which is shown in Figure 1.1. Elements in this group are called alkaline Earth metals. These metals are silver or gray in color. They are relatively soft and low in density, although not as soft and lightweight as alkali metals.

examples of alkaline earth metals

For a better understanding of alkaline Earth metals, lets take a closer look at two of them: calcium (Ca) and strontium (Sr). Calcium is a soft, gray, nontoxic alkaline Earth metal. Although pure calcium doesnt exist in nature, calcium compounds are very common in Earths crust and in sea water. Calcium is also the most abundant metal in the human body, occurring as calcium compounds such as calcium phosphate and calcium carbonate. These calcium compounds are found in bones and make them hard and strong. The skeleton of the average adult contains about a kilogram of calcium. Because calciumlike bariumabsorbs x-rays, bones show up white in x-ray images. Calcium is an important component of a healthy human diet. Good food sources of calcium are pictured in Figure Q: What health problems might result from a diet low in calcium? A: Children who dont get enough calcium while their bones are forming may develop a deficiency disease called rickets, in which their bones are softer than normal and become bent and stunted. Adults who dont get enough calcium may develop a condition called osteoporosis, in which the bones lose calcium and become weak and brittle. People with osteoporosis are at high risk of bone fractures. Strontium is a silver-colored alkaline Earth metal that is even softer than calcium. Strontium compounds are quite common and have a variety of usesfrom fireworks to cement to toothpaste. In fireworks, strontium compounds produce deep red explosions. In toothpaste, the compound strontium chloride reduces tooth sensitivity.

instructional diagrams

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questions

all of the following are alkaline earth metals except

a) barium.

-->  b) sodium.

c) calcium.

d) magnesium.

properties of alkaline earth metals include

a) gray or silver color.

b) low density.

c) softness.

-->  d) all of the above

all alkaline earth metals have three valence electrons.

a. true

-->  b. false

alkaline earth metals are the most reactive metals.

a. true

-->  b. false

alkaline earth metals never exist as pure substances in nature.

-->  a. true

b. false

diets that are too low in calcium may lead to

a) rickets.

b) osteoporosis.

c) bone fractures.

-->  d) all of the above

diagram questions

No diagram questions associated with this lesson