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Hydrogen and also Alkali Metals
Characteristics of team 1 of the periodic table.
You are watching: How many valence electrons do the alkaline earth metals possess?
· identify theelementsin group 1 the the periodic table.
· define why team 1elementsare very reactive.
· List other properties that alkalimetals.
You more than likely think ofwateras a problem that deserve to put the end fires. However someelementsare therefore reactive that they burn in water. In fact, they basically explode in water. That’s what is continue in the photo above. Around 3 pounds of salt were included to water, and also the result was this explosive reaction. Why is salt such a reactive element? In this lesson you will discover out.
The an initial Group
Sodium (Na) is an element in group 1 of the periodic table that the elements. This team (column) that the table is shown below. It contains the nonmetal hydrogen (H) and sixmetalsthat space calledalkali metals. Elements in the same team of the periodic table have the same variety of valenceelectrons. These room the electron in their outerenergy levelthat have the right to be associated in chemistry reactions. Valence electrons determine many of the nature of an element, so aspects in the same group have comparable properties. All the elements in group 1 have just one valence electron. This provides them really reactive.
Q:Why does having just one valence electron make group 1 elements very reactive?
A:With simply one valence electron, group 1 elements are “eager” to shed that electron. Act so enables them to achieve a complete outerenergy leveland best stability.
Reactivity of team 1 Elements
Hydrogen is a an extremely reactive gas, and the alkalimetalsare even an ext reactive. In fact, they room the many reactive metals and, in addition to the aspects in team 17, space the most reactive of every elements. The reactivity of alkali metals boosts from the peak to the bottom the the group, so lithium (Li) is the the very least reactive alkali metal and also francium (Fr) is the many reactive. Due to the fact that alkali steels are therefore reactive, they are discovered in nature only in mix with various other elements. They often combine with group 17 elements, which are very “eager” to gain an electron. In ~ the URL below, you deserve to watch a video clip that reflects just just how reactive the alkali steels are.
http://youtu.be/uixxJtJPVXk(2:22)
Other properties of Alkali Metals
Besides being really reactive, alkali steels share a number of other properties.
· Alkali metals are allsolidsat roomtemperature.
· Alkali steels are low in density, and some of castle float onwater.
· Alkali metals are fairly soft. Some are also soft enough to cut with a knife, like the sodium pictured in theFigurebelow.
A Closer Look
Although all team 1 elements share details properties, such as being really reactive, they are not alike in every way. Three various group 1 facets are explained in an ext detail below (Figuresbelow,below, andbelow). Notification the ways in which they differ from one another.
Hydrogen has the smallest, lightest atom of every elements. Pure hydrogen is a colorless, odorless, tasteless gas the is nontoxic yet highly flammable. Hydrogen gas exists greatly as diatomic (“two-atom”) molecules (H2), as presented in the diagram on the right. Hydrogen is the many abundant facet in the universe and the third most abundant element on Earth, emerging mainly in compound such as water.
Q:Why execute you think hydrogen gas generally exists as diatomic molecules?
A:Each hydrogen atom has actually just one electron. As soon as two hydrogenatomsbond together, lock share a pair ofelectrons. The shared electrons fill their onlyenergy level, providing them the many stable setup of electrons.
Potassium is a soft, silvery metal that ignites explosively in water. It easily loses that is one valence electron to kind positive potassium ions (K+), which are required by all living cells. Potassium is so vital for plants the it is discovered in nearly all fertilizers, favor the one presented here. Potassium is abundant in Earth’s crust in minerals such together feldspar.
Francium has actually one of the largest, heaviest atom of every elements. That one valence electron is much removed native the nucleus, together you can see in the atomic version on the right, so that is quickly removed native the atom. Francium is radioactive and also quickly decays to form other aspects such as radium. This is why francium is very rare in nature. Much less than an ounce of francium is existing on earth at any given time.
Q:Francium decays too easily to formcompoundswith various other elements. Which facets to friend think it would certainly bond v if the could?
A:With one valence electron, francium would certainly bond through a halogen facet in group 17, which has seven valenceelectronsand needs one an ext to fill its outer power level. Elements in group 17 incorporate fluorine and also chlorine.
Summary
· team 1 the the routine table consists of hydrogen and the alkali metals.
· due to the fact that they have actually just one valence electron, group 1 elements are really reactive. As a result, lock are found in nature just in combination with various other elements.
· Alkali steels are allsolidsat roomtemperature. Lock are reasonably soft and also low in density.
· from the top to the bottom of group 1, the elements have heavier, an ext reactiveatoms.
Explore More
At the adhering to URL, click “Group 1 data and also graphs.” use the data in the team 1 table to to fill in the blanks listed below with eitherincreasesordecreases.
http://www.docbrown.info/page07/sblock.htm
From the optimal to the bottom of team 1, nature of the alkali metals adjust as follows:
1. Melting allude __________.
2. Boiling allude __________.
3. Density __________.
4. Atom radius __________.
5. Variety of electrons __________.
Review
1. What room alkali metals?
2. Why is hydrogen, a nonmetal, placed in the same group as the alkali metals?
3. Define why group 1 aspects often formcompoundswith facets in team 17.
4. Compare and also contrast hydrogen and also francium.
Alkaline planet Metals
Characteristics of group 2 the the routine table.
· recognize alkaline Earthmetals.
· perform properties that alkaline Earthmetals.
· define why alkaline Earthmetalsare really reactive.
Sparklers favor the one this girl is holding make festive additions to countless celebrations. You may use castle yourself. Yet watch the end if friend do since their flames space really hot! The shining white flames are created when magnesium burns. Magnesium is a light- weight metal that burns in ~ a very hightemperature. Other uses of magnesium encompass flash photography, flares, and also fireworks. Magnesium is a metal in group 2 the the regular table, which you will read around in this concept.
The 2nd Group
Barium (Ba) is one of sixelementsin team 2 that the routine table, i m sorry is shown below. Facets in this group are calledalkaline earth metals. These steels are silver- or gray incolor. They are relatively soft and low in density, although no as soft and also lightweight together alkali metals. You can watch a brief video introduction to the alkaline planet metals at this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.
Reactivity the Alkaline planet Metals
All alkaline planet metals have similar properties due to the fact that they all have two valenceelectrons. Castle readily offer up their 2 valence electron to achieve a complete outerenergy level, i m sorry is the many stable setup of electrons. Together a result, they are really reactive, back not fairly as reactive together the alkali steels in group 1. Because that example, alkaline earth metals will react with coldwater, but not explosively as alkali steels do. Because of their reactivity, alkaline earth metals never exist together puresubstancesin nature. Instead, lock are always found merged with otherelements.
The reactivity of alkaline planet metals increases from the optimal to the bottom that the group. That’s due to the fact that theatomsget bigger native the optimal to the bottom, therefore the valenceelectronsare farther indigenous the nucleus. When valence electrons space farther indigenous the nucleus, they space attracted much less strongly by the cell nucleus and much more easily removed from the atom. This renders the atom more reactive.
Q:Alkali metals have just one valence electron. Why space alkaline earth metals much less reactive than alkali metals?
A:It takes much more energy to remove two valenceelectronsfrom an atom 보다 one valence electron. This makes alkaline planet metals with their two valence electrons much less reactive 보다 alkali steels with their one valence electron.
Examples the Alkaline earth Metals
For a much better understanding the alkaline earth metals, let’s take it a closer look at two of them: calcium (Ca) and also strontium (Sr). Calcium is a soft, gray, nontoxic alkaline earth metal. Back pure calcium doesn’t exist in nature, calciumcompoundsare really common in Earth’s crust and also in seawater. Calcium is additionally the many abundant metal in the human body, occurring as calcium compound such as calcium phosphate and also calcium carbonate. This calcium compounds are discovered in bones and make them hard and also strong. The skeleton that the median adult contains about a kilogram that calcium. Since calcium—like barium—absorbs x-rays, bones display up white in x-ray images. Calcium is crucial component that a healthy and balanced human diet. Great food sources of calcium room pictured inFigurebelow.
Q:What health difficulties might an outcome from a diet short in calcium?
A:Children who don’t get enough calcium while your bones are creating may build a deficiency condition called rickets, in which your bones space softer than normal and become bent and also stunted. Adults who don’t get enough calcium may develop a condition called osteoporosis, in i m sorry the bones shed calcium and also become weak and also brittle. World with osteoporosis room at high threat of bone fractures.
Strontium is a silver-colored alkaline planet metal the is even softer 보다 calcium. Strontiumcompoundsare rather common and have a range of uses—from fireworks to cement to toothpaste. In fireworks, strontium compounds develop deep red explosions. In toothpaste, choose the one pictured in theFigurebelow, the link strontium chloride reduces tooth sensitivity.
Summary
· elements in team 2 the the routine table are called alkaline planet metals. They space silvery or gray incolor. They room also fairly soft and also low in density.
· Alkaline planet metals are an extremely reactive due to the fact that they readily offer up their two valence electron to attain a full outerenergy level, which is the many stable setup of electrons. Reactivity boosts from the optimal to the bottom of the group.
· instances of alkaline planet metals incorporate calcium, which is essential for solid bones, and also strontium, i m sorry is offered for make cement and also other products.
Explore More
At the following URL, observe just how four various alkaline planet metals react withwater. After you clock the video, answer the questions below.
http://www.youtube.com/watch?v=B2ZPrg9IVEo(0:16)
1. Watch the reactions in the video, and also then location the alkaline planet metals from many to the very least reactive through water.
2. What explains the differences in reactivity?
3. Predict the reactivity of beryllium through water. Where would that fit in her ranking?
4. Whatsubstancesare produced in each reaction that you observed in the video?
Review
1. What room alkaline earth metals? What are their physical properties?
2. Why space alkaline planet metals really reactive?
3. Compare and also contrast the reactivity the beryllium (Be) and barium (Ba).
Noble Gases
Characteristics of group 18 that the periodic table.
· identify the noblegases.
· perform properties that noblegases.
· explain the nonreactivity that noblegasesand exactly how it is pertained to theoctet rule.
Okay, helium balloons room light, but they’re no that light! This fanciful picture serves to do the allude that helium is just one of the lightestelements. Helium belongs to a team of facets called the noble gases.
What are Noble Gases?
Noble gasesare nonreactive, nonmetallicelementsin team 18 that the periodic table. As you deserve to see in the routine table inFigurebelow, noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and also radon (Rn). Every noble gases room colorless and odorless. They also have lowboilingpoints, explaining why they space gases at roomtemperature. Radon, in ~ the bottom of the group, is radioactive, so that constantly decays to otherelements. For terrific overview the the noble gases, watch the video at this URL:
http://www.youtube.com/watch?v=jdzBRmLsUM8(4:53)
· come learn just how the noble gases to be discovered, walk to this URL:http://www.youtube.com/watch?v=ceQMs30D16E.
· come explore particular noble gases, click their symbols in the periodic table in ~ this URL:http://www.ptable.com/.
Q:Based on their place in the regular table (Figureabove), how numerous valenceelectronsdo friend think noble gases have?
A:The number of valenceelectronsstarts at one for facets in group 1. That then boosts by one indigenous left come right across each period (row) that the routine table for groups 1–2 and also 13–18. Therefore, noble gases have eight valence electrons.
Chemical nature of Noble Gases
Noble gases are the least reactive that all well-known elements. That’s due to the fact that with eight valenceelectrons, your outer power levels room full. The only exemption is helium, which has actually just two electrons. Yet helium additionally has a full outerenergy level, due to the fact that its only power level (energy level 1) deserve to hold a best of 2 electrons. A full outer energy level is the many stable plan of electrons. As a result, noble gases cannot become an ext stable by reacting with various other elements and also gaining or shedding valence electrons. Therefore, noble gases room rarely involved inchemical reactionsand nearly never formcompoundswith other elements.
Noble Gases and also theOctet Rule
Because the noble gases space the least reactive of all elements, your eight valence electron are offered as the traditional for nonreactivity and to define how other facets interact. This is stated as the octet (“group the eight”) rule. Follow to this rule,atomsreact come formcompoundsthat permit them to have a team of eight valence electrons prefer the noble gases. Because that example, salt (with one valence electron) reacts v chlorine (with 7 valence electrons) to type the stable compound salt chloride (table salt). In this reaction, sodium donates one electron and chlorine accepts it, providing each element an octet the valence electrons.
Some uses of Noble Gases
Did you ever before get helium balloons like those in the opening picture? unlike a balloon filled through air, a balloon filled through helium demands to be weighted under so that won’t float far — although you don’t have to use an elephant!.
Q:Why does a helium balloon float away if it’s not weighted down?
A:Heliumatomshave just twoprotons, twoneutrons, and two electrons, so they have actually less mass than any kind of other atoms except hydrogen. As a result, helium is lighter than air, explaining why a helium balloon floats up right into the air unless weighted down.
Early incandescent light bulbs, favor the one pictured in theFigurebelow, didn’t last very long. The filaments quickly melted out. Back air to be pumped out of the bulb, that wasn’t a complete vacuum. Oxygen in the small amount that air remaining inside the light pear reacted through the steel filament. This corroded the filament and caused dark store on the glass. Filling a irradiate bulb with argon gas avoids these problems. That’s why modern-day light bulbs room filled with argon.
Q:How go argon avoid the troubles of at an early stage light bulbs?
A:As a noble gas v eight electrons, argon doesn’t react v the steel in the filament. This protects the filament and also keeps the glass blub complimentary of deposits.
Noble gases are also used to to fill the glass tube of lighted signs like the one in theFigurebelow. Back noble gases are chemically nonreactive, your electrons deserve to be energized by sending out anelectric currentthrough them. Once this happens, the electrons run to a higherenergy level. Once the electrons return to their original power level, they provide off power as light. Different noble gases provide off light of various colors. Neon provides off reddish-orange light, like the native “Open” in the sign below. Krypton offers off violet light and also xenon offers off blue light.
Summary
· Noble gases space nonreactive, nonmetallic elements in team 18 that the regular table.
· Noble gases are the least reactive of all elements. That’s due to the fact that they have eight valence electrons, which to fill their outerenergy level. This is the many stable setup of electrons, therefore noble gases seldom react with various other elements and also formcompounds.
· Theoctet rulestates thatatomsreact to form compounds that allow them to have eight valence electrons like the noble gases, which are the the very least reactive elements.
· Noble gases are provided for balloons, irradiate bulbs, and also lighted signs.
Explore More
Watch the video about noble gases in ~ the complying with URL, and then answer the concerns below.
http://www.open.edu/openlearn/science-maths-technology/science/chemistry/noble-gases
1. Compare and also contrast the reactivity the the facets helium, neon, argon, krypton, and xenon.
2. Compare the density of these noble gases come the density of air.
3. Define how the mass of noble gases alters from the top to the bottom of team 18.
Review
1. What are noble gases?
2. Define why noble gases are almost totally nonreactive.
See more: Which Life Cycle Components Appear Only In Mosses And Ferns? ?
3. What is the octet rule? how is it related to noble gases?
4. Hydrogen (H) atoms have one electron and exist together diatomic (“two-atom”) molecules (H2). Helium atoms have actually two electrons and exist just as solitary helium atoms. Define why hydrogen and also helium differ in this way.