assignments unit 3 part 3

Hydrogen and also alkali metals

Alkali earth metals

Nobel gases

Hydrogen and Alkali Metals

Characteristics of team 1 that the periodic table.

You are watching: Most reactive group on periodic table

· determine theelementsin team 1 that the routine table.

· define why team 1elementsare really reactive.

· List various other properties that alkalimetals.


You most likely think ofwateras a substance that deserve to put the end fires. However someelementsare so reactive that they burn in water. In fact, they essentially explode in water. That’s what is continue in the photograph above. About 3 pounds of salt were added to water, and also the result was this explosive reaction. Why is salt such a reactive element? In this lesson friend will uncover out.

The very first Group

Sodium (Na) is an facet in team 1 the the regular table of the elements. This group (column) the the table is presented below. It has the nonmetal hydrogen (H) and sixmetalsthat room calledalkali metals. Aspects in the same group of the regular table have actually the same number of valenceelectrons. These are the electrons in your outerenergy levelthat have the right to be connected in chemistry reactions. Valence electrons determine plenty of of the nature of one element, so aspects in the same team have similar properties. All the elements in team 1 have just one valence electron. This provides them an extremely reactive.

Q:Why does having just one valence electron make team 1 elements very reactive?

A:With just one valence electron, team 1 elements are “eager” to shed that electron. Law so permits them to attain a complete outerenergy leveland best stability.


Reactivity of team 1 Elements

Hydrogen is a an extremely reactive gas, and also the alkalimetalsare even an ext reactive. In fact, they room the many reactive metals and, along with the facets in group 17, room the many reactive of all elements. The reactivity the alkali metals rises from the peak to the bottom that the group, therefore lithium (Li) is the least reactive alkali metal and francium (Fr) is the most reactive. Because alkali steels are so reactive, they are uncovered in nature just in mix with other elements. Lock often combine with team 17 elements, i beg your pardon are an extremely “eager” to acquire an electron. In ~ the URL below, you have the right to watch a video clip that shows just just how reactive the alkali metals are.


Other nature of Alkali Metals

Besides being an extremely reactive, alkali metals share a variety of other properties.

· Alkali metals are allsolidsat roomtemperature.

· Alkali metals are short in density, and also some of lock float onwater.

· Alkali metals are fairly soft. Some are also soft sufficient to cut with a knife, choose the salt pictured in theFigurebelow.


A Closer Look

Although all team 1 aspects share certain properties, such as being very reactive, they room not alike in every way. Three different group 1 elements are defined in much more detail below (Figuresbelow,below, andbelow). An alert the methods in i beg your pardon they different from one another.


Hydrogen has actually the smallest, lightest atoms of every elements. Pure hydrogen is a colorless, odorless, tasteless gas that is nontoxic however highly flammable. Hydrogen gas exists mostly as diatomic (“two-atom”) molecule (H2), as displayed in the diagram on the right. Hydrogen is the many abundant facet in the universe and the third most abundant element on Earth, developing mainly in compounds such as water.

Q:Why perform you think hydrogen gas generally exists as diatomic molecules?

A:Each hydrogen atom has just one electron. Once two hydrogenatomsbond together, lock share a pair ofelectrons. The mutual electrons to fill their onlyenergy level, giving them the most stable arrangement of electrons.


Potassium is a soft, silvery steel that ignites explosively in water. It quickly loses its one valence electron to kind positive potassium ions (K+), i m sorry are necessary by every living cells. Potassium is so essential for plants the it is found in practically all fertilizers, like the one displayed here. Potassium is numerous in Earth’s crust in minerals such together feldspar.


Francium has actually one of the largest, heaviest atom of all elements. Its one valence electron is far removed from the nucleus, together you can see in the atomic version on the right, so the is conveniently removed indigenous the atom. Francium is radioactive and quickly decays to form other elements such together radium. This is why francium is incredibly rare in nature. Less than an ounce of francium is current on earth at any type of given time.

Q:Francium decays too conveniently to formcompoundswith other elements. Which facets to you think it would certainly bond v if the could?

A:With one valence electron, francium would certainly bond through a halogen facet in team 17, which has seven valenceelectronsand demands one much more to to fill its outer power level. Facets in team 17 incorporate fluorine and also chlorine.


· group 1 the the periodic table includes hydrogen and the alkali metals.

· because they have actually just one valence electron, team 1 facets are very reactive. Together a result, lock are found in nature just in mix with various other elements.

· Alkali metals are allsolidsat roomtemperature. Castle are fairly soft and also low in density.

· indigenous the height to the bottom of team 1, the aspects have heavier, more reactiveatoms.

Explore More

At the following URL, click on “Group 1 data and graphs.” usage the data in the group 1 table to fill in the blanks below with eitherincreasesordecreases.


From the height to the bottom of group 1, properties of the alkali metals readjust as follows:

1. Melting point __________.

2. Boiling allude __________.

3. Density __________.

4. Atom radius __________.

5. Variety of electrons __________.


1. What room alkali metals?

2. Why is hydrogen, a nonmetal, inserted in the same team as the alkali metals?

3. Explain why team 1 elements often formcompoundswith aspects in team 17.

4. Compare and also contrast hydrogen and also francium.

Alkaline earth Metals

Characteristics of group 2 of the routine table.

· determine alkaline Earthmetals.

· list properties that alkaline Earthmetals.

· define why alkaline Earthmetalsare an extremely reactive.


Sparklers prefer the one this girl is holding make festive enhancements to many celebrations. You may use castle yourself. But watch out if girlfriend do since their flames room really hot! The glowing white flames are produced when magnesium burns. Magnesium is a light- weight metal that burns in ~ a very hightemperature. Other offers of magnesium incorporate flash photography, flares, and fireworks. Magnesium is a metal in group 2 of the periodic table, i m sorry you will read around in this concept.  

The 2nd Group

Barium (Ba) is one of sixelementsin team 2 the the periodic table, which is shown below. Aspects in this group are calledalkaline planet metals. These metals are silver or gray incolor. Lock are relatively soft and also low in density, although not as soft and also lightweight as alkali metals. You have the right to watch a brief video introduction come the alkaline earth metals in ~ this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.


Reactivity that Alkaline planet Metals

All alkaline planet metals have similar properties since they all have actually two valenceelectrons. Lock readily provide up their two valence electrons to accomplish a complete outerenergy level, i m sorry is the many stable setup of electrons. Together a result, lock are very reactive, back not quite as reactive as the alkali steels in group 1. Because that example, alkaline earth metals will certainly react through coldwater, yet not explosively as alkali steels do. Due to the fact that of their reactivity, alkaline earth metals never ever exist as puresubstancesin nature. Instead, lock are constantly found combined with otherelements.

The reactivity of alkaline earth metals boosts from the peak to the bottom the the group. That’s since theatomsget bigger native the optimal to the bottom, so the valenceelectronsare farther indigenous the nucleus. As soon as valence electrons room farther native the nucleus, they are attracted much less strongly through the cell nucleus and much more easily eliminated from the atom. This provides the atom much more reactive.

Q:Alkali metals have just one valence electron. Why space alkaline earth metals less reactive than alkali metals?

A:It takes more energy to eliminate two valenceelectronsfrom an atom than one valence electron. This provides alkaline planet metals v their two valence electrons less reactive 보다 alkali steels with their one valence electron.

Examples of Alkaline planet Metals

For a much better understanding the alkaline planet metals, let’s take it a closer look at at two of them: calcium (Ca) and strontium (Sr). Calcium is a soft, gray, nontoxic alkaline planet metal. Although pure calcium doesn’t exist in nature, calciumcompoundsare very common in Earth’s crust and also in seawater. Calcium is also the most abundant steel in the person body, occurring as calcium compounds such as calcium phosphate and calcium carbonate. These calcium link are discovered in bones and make them hard and strong. The skeleton the the average adult contains about a kilogram the calcium. Since calcium—like barium—absorbs x-rays, bones present up white in x-ray images. Calcium is an important component the a healthy human diet. Good food resources of calcium are pictured inFigurebelow.


Q:What health troubles might an outcome from a diet short in calcium?

A:Children that don’t get sufficient calcium while their bones are creating may build a deficiency condition called rickets, in which your bones are softer than normal and also become bent and stunted. Adults that don’t get enough calcium may develop a problem called osteoporosis, in i beg your pardon the bones lose calcium and become weak and brittle. Civilization with osteoporosis space at high threat of bone fractures.

Strontium is a silver-colored alkaline planet metal the is also softer 보다 calcium. Strontiumcompoundsare quite common and also have a variety of uses—from fireworks to cement come toothpaste. In fireworks, strontium compounds produce deep red explosions. In toothpaste, like the one pictured in theFigurebelow, the link strontium chloride reduces tooth sensitivity.



· facets in group 2 that the regular table are called alkaline planet metals. They room silvery or gray incolor. They space also fairly soft and low in density.

· Alkaline planet metals are very reactive because they readily give up their 2 valence electrons to attain a full outerenergy level, i beg your pardon is the many stable plan of electrons. Reactivity boosts from the peak to the bottom that the group.

· instances of alkaline planet metals incorporate calcium, which is necessary for solid bones, and also strontium, which is supplied for make cement and also other products.

Explore More

At the adhering to URL, observe how four various alkaline earth metals reaction withwater. After you watch the video, price the questions below.


1. Watch the reaction in the video, and also then location the alkaline earth metals from many to the very least reactive with water.

2. What explains the differences in reactivity?

3. Guess the reactivity of beryllium with water. Whereby would the fit in your ranking?

4. Whatsubstancesare developed in each reaction the you it was observed in the video?


1. What space alkaline earth metals? What room their physics properties?

2. Why space alkaline earth metals an extremely reactive?

3. Compare and contrast the reactivity that beryllium (Be) and barium (Ba).

Noble Gases

Characteristics of group 18 the the routine table.

· identify the noblegases.

· perform properties that noblegases.

· describe the nonreactivity that noblegasesand just how it is concerned theoctet rule.


Okay, helium balloons are light, yet they’re not that light! This fanciful photo serves to make the allude that helium is just one of the lightestelements. Helium belongs come a group of facets called the noble gases.

What room Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin group 18 that the regular table. Together you have the right to see in the regular table inFigurebelow, noble gases incorporate helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and also radon (Rn). All noble gases room colorless and also odorless. They additionally have lowboilingpoints, explaining why they room gases in ~ roomtemperature. Radon, at the bottom the the group, is radioactive, so that constantly decays to otherelements. For wonderful overview the the noble gases, watch the video clip at this URL:


· to learn how the noble gases were discovered, walk to this URL:http://www.youtube.com/watch?v=ceQMs30D16E.

· to explore particular noble gases, click their symbols in the routine table in ~ this URL:http://www.ptable.com/.


Q:Based ~ above their position in the periodic table (Figureabove), how countless valenceelectronsdo you think noble gases have?

A:The number of valenceelectronsstarts in ~ one for facets in team 1. The then rises by one indigenous left come right across each period (row) the the routine table for groups 1–2 and 13–18. Therefore, noble gases have actually eight valence electrons.

Chemical nature of Noble Gases

Noble gases are the least reactive that all recognized elements. That’s due to the fact that with eight valenceelectrons, your outer energy levels space full. The only exemption is helium, which has actually just 2 electrons. Yet helium also has a full outerenergy level, since its only energy level (energy level 1) can hold a best of 2 electrons. A full outer power level is the most stable plan of electrons. Together a result, noble gases can not become more stable by reaction with various other elements and gaining or shedding valence electrons. Therefore, noble gases space rarely involved inchemical reactionsand practically never formcompoundswith other elements.

Noble Gases and theOctet Rule

Because the noble gases room the least reactive of all elements, their eight valence electrons are supplied as the traditional for nonreactivity and to describe how other aspects interact. This is stated as the octet (“group of eight”) rule. According to this rule,atomsreact come formcompoundsthat permit them to have a group of eight valence electrons like the noble gases. Because that example, salt (with one valence electron) reacts with chlorine (with 7 valence electrons) to kind the stable compound sodium chloride (table salt). In this reaction, salt donates an electron and chlorine accepts it, giving each element an octet the valence electrons.

Some uses of Noble Gases

Did you ever get helium balloons choose those in the opened picture? uneven a balloon filled v air, a balloon filled through helium requirements to it is in weighted under so that won’t float away — although girlfriend don’t need to use an elephant!.

Q:Why walk a helium balloon float away if it’s not weighted down?

A:Heliumatomshave simply twoprotons, twoneutrons, and two electrons, so they have actually less massive than any other atoms except hydrogen. Together a result, helium is lighter 보다 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 really long. The filaments quickly burned out. Return air to be pumped the end of the bulb, it wasn’t a finish vacuum. Oxygen in the tiny amount the air continuing to be inside the light pear reacted through the steel filament. This corroded the filament and also caused dark deposits on the glass. Filling a light bulb with argon gas stays clear of these problems. That’s why contemporary light bulbs room filled with argon.

Q:How walk argon protect against the troubles of early light bulbs?

A:As a noble gas through eight electrons, argon doesn’t react v the metal in the filament. This protects the filament and also keeps the glass blub totally free of deposits.


Noble gases are also used to to fill the glass tube of lighted signs like the one in theFigurebelow. Although noble gases space chemically nonreactive, your electrons can be energized by sending anelectric currentthrough them. As soon as this happens, the electrons jump to a higherenergy level. As soon as the electrons return to their original power level, they provide off energy as light. Different noble gases provide off light of different colors. Neon offers off reddish-orange light, favor the indigenous “Open” in the authorize below. Krypton offers off violet light and xenon offers off blue light.



· Noble gases space nonreactive, nonmetallic elements in team 18 that the routine table.

· Noble gases room the the very least reactive of every elements. That’s because they have eight valence electrons, which to fill their outerenergy level. This is the many stable setup of electrons, so noble gases hardly ever react with other elements and also formcompounds.

· Theoctet rulestates thatatomsreact to kind compounds that permit them to have eight valence electrons favor the noble gases, which room the least reactive elements.

· Noble gases are provided for balloons, light bulbs, and lighted signs.

Explore More

Watch the video clip about noble gases at the adhering to URL, and also then price the questions below.


1. Compare and contrast the reactivity of the elements helium, neon, argon, krypton, and also xenon.

2. To compare the density of these noble gases come the density of air.

3. Define how the massive of noble gases changes from the top to the bottom of group 18.


1. What space noble gases?

2. Explain why noble gases space almost fully nonreactive.

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3. What is the octet rule? exactly how is it concerned noble gases?

4. Hydrogen (H) atoms have one electron and also exist as diatomic (“two-atom”) molecule (H2). Helium atoms have actually two electrons and exist just as single helium atoms. Define why hydrogen and helium different in this way.