assignments unit 3 part 3

Hydrogen and also alkali metals

Alkali earth metals

Nobel gases

Hydrogen and also Alkali Metals

Characteristics of team 1 of the regular table.

You are watching: Which element is the least reactive

· identify theelementsin group 1 the the regular table.

· explain why team 1elementsare an extremely reactive.

· List various other properties that alkalimetals.


You more than likely think ofwateras a problem that can put out fires. But someelementsare for this reason reactive the they burn in water. In fact, they virtually explode in water. That’s what is keep going in the photo above. About 3 pounds of salt were included to water, and also the an outcome was this explosive reaction. Why is salt such a reactive element? In this lesson friend will discover out.

The an initial Group

Sodium (Na) is an aspect in group 1 the the routine table the the elements. This group (column) the the table is shown below. It consists of the nonmetal hydrogen (H) and sixmetalsthat room calledalkali metals. Elements in the same group of the regular table have actually the same variety of valenceelectrons. These are the electron in their outerenergy levelthat can be involved in chemistry reactions. Valence electrons determine many of the properties of an element, so facets in the same team have similar properties. Every the elements in group 1 have just one valence electron. This provides them really reactive.

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

A:With just one valence electron, team 1 facets are “eager” to lose that electron. Doing so permits them to attain a full outerenergy leveland best stability.


Reactivity of group 1 Elements

Hydrogen is a an extremely reactive gas, and also the alkalimetalsare even much more reactive. In fact, they room the most reactive metals and, in addition to the facets in group 17, room the many reactive of every elements. The reactivity of alkali metals boosts from the optimal to the bottom the the group, so lithium (Li) is the the very least reactive alkali metal and francium (Fr) is the many reactive. Due to the fact that alkali steels are so reactive, lock are discovered in nature just in mix with other elements. Castle often integrate with group 17 elements, i m sorry are really “eager” to get an electron. At the URL below, you have the right to watch a video clip that mirrors just just how reactive the alkali metals are.


Other nature of Alkali Metals

Besides being very reactive, alkali steels share a variety of other properties.

· Alkali steels are allsolidsat roomtemperature.

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

· Alkali metals are reasonably soft. Some are also soft sufficient to reduced with a knife, choose the sodium pictured in theFigurebelow.


A Closer Look

Although all team 1 elements share certain properties, such together being very reactive, they space not alike in every way. Three various group 1 facets are described in more detail below (Figuresbelow,below, andbelow). An alert the methods in i beg your pardon they differ from one another.


Hydrogen has the smallest, lightest atom of all elements. Pure hydrogen is a colorless, odorless, tasteless gas the is nontoxic yet highly flammable. Hydrogen gas exists mostly as diatomic (“two-atom”) molecules (H2), as shown in the diagram on the right. Hydrogen is the most abundant aspect in the universe and also the 3rd most abundant element on Earth, arising mainly in link such as water.

Q:Why execute you think hydrogen gas normally exists together diatomic molecules?

A:Each hydrogen atom has actually just one electron. As soon as two hydrogenatomsbond together, lock share a pair ofelectrons. The common electrons fill their onlyenergy level, providing them the many stable plan of electrons.


Potassium is a soft, silvery steel that ignites explosively in water. It conveniently loses its one valence electron to kind positive potassium ion (K+), i m sorry are required by all living cells. Potassium is so necessary for plants that it is uncovered in nearly all fertilizers, prefer the one displayed here. Potassium is abundant in Earth’s crust in minerals such together feldspar.


Francium has actually one that the largest, heaviest atoms of all elements. That one valence electron is far removed from the nucleus, as you have the right to see in the atomic model on the right, so the is easily removed indigenous the atom. Francium is radioactive and quickly decays to kind other facets such as radium. This is why francium is very rare in nature. Less than an ounce of francium is present on planet at any type of given time.

Q:Francium decays too easily to formcompoundswith other elements. Which elements to girlfriend think it would bond through if it could?

A:With one valence electron, francium would bond v a halogen element in team 17, which has seven valenceelectronsand needs one much more to to fill its outer energy level. Facets in team 17 include fluorine and also chlorine.


· group 1 the the regular table contains hydrogen and the alkali metals.

· due to the fact that they have actually just one valence electron, team 1 elements are very reactive. Together a result, they are uncovered in nature just in mix with other elements.

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

· native the height to the bottom of team 1, the facets have heavier, more reactiveatoms.

Explore More

At the adhering to URL, click on “Group 1 data and also graphs.” usage the data in the team 1 table to to fill in the blanks listed below with eitherincreasesordecreases.


From the height to the bottom of team 1, properties of the alkali metals adjust as follows:

1. Melting allude __________.

2. Boiling allude __________.

3. Density __________.

4. Atomic radius __________.

5. Variety of electrons __________.


1. What room alkali metals?

2. Why is hydrogen, a nonmetal, placed in the same group as the alkali metals?

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

4. Compare and also contrast hydrogen and francium.

Alkaline planet Metals

Characteristics of group 2 the the routine table.

· determine alkaline Earthmetals.

· perform properties of alkaline Earthmetals.

· describe why alkaline Earthmetalsare really reactive.


Sparklers choose the one this girl is holding do festive enhancements to many celebrations. You may use lock yourself. But watch out if friend do since their flames are really hot! The bright white flames are developed when magnesium burns. Magnesium is a light- weight steel that burns in ~ a really hightemperature. Other supplies of magnesium encompass flash photography, flares, and fireworks. Magnesium is a steel in team 2 the the regular table, i m sorry you will read about in this concept.  

The 2nd Group

Barium (Ba) is just one of sixelementsin team 2 that the regular table, i beg your pardon is displayed below. Elements in this team are calledalkaline earth metals. These steels are silver or gray incolor. Lock are fairly soft and low in density, although not as soft and also lightweight together alkali metals. You have the right to watch a brief video clip introduction come the alkaline earth metals at this URL:http://www.youtube.com/watch?v=DFQPnHkQlZM.


Reactivity that Alkaline planet Metals

All alkaline planet metals have comparable properties because they all have actually two valenceelectrons. Castle readily give up their 2 valence electrons to attain a complete outerenergy level, which is the many stable setup of electrons. As a result, lock are really reactive, although not fairly as reactive together the alkali steels in team 1. For example, alkaline planet metals will react through coldwater, however not explosively as alkali metals do. Due to the fact that of their reactivity, alkaline planet metals never ever exist as puresubstancesin nature. Instead, castle are always found an unified with otherelements.

The reactivity that alkaline planet metals boosts from the peak to the bottom that the group. That’s since theatomsget bigger native the peak to the bottom, for this reason the valenceelectronsare farther indigenous the nucleus. When valence electrons room farther indigenous the nucleus, they are attracted much less strongly through the cell core and much more easily gotten rid of from the atom. This makes the atom much more reactive.

Q:Alkali metals have just one valence electron. Why room alkaline planet metals much less reactive 보다 alkali metals?

A:It takes much more energy to remove two valenceelectronsfrom an atom than one valence electron. This renders alkaline planet metals through their two valence electrons much less reactive 보다 alkali metals with their one valence electron.

Examples that Alkaline planet Metals

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


Q:What health difficulties might an outcome from a diet low in calcium?

A:Children who don’t get enough calcium while your bones are creating may develop a deficiency disease called rickets, in which their bones room 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 shed calcium and also become weak and brittle. Civilization with osteoporosis space at high threat of bone fractures.

Strontium is a silver-colored alkaline planet metal the is even softer 보다 calcium. Strontiumcompoundsare fairly common and also have a range of uses—from fireworks come cement come toothpaste. In fireworks, strontium compounds develop deep red explosions. In toothpaste, like the one pictured in theFigurebelow, the compound strontium chloride reduces this sensitivity.



· aspects in group 2 of the periodic table are called alkaline planet metals. They space silvery or gray incolor. They space also fairly soft and also low in density.

· Alkaline earth metals are very reactive due to the fact that they readily provide up their two valence electron to achieve a full outerenergy level, which is the most stable plan of electrons. Reactivity increases from the top to the bottom that the group.

· instances of alkaline earth metals incorporate calcium, i beg your pardon is needed for strong bones, and strontium, i beg your pardon is used for make cement and other products.

Explore More

At the following URL, observe exactly how four different alkaline earth metals reaction withwater. After you watch the video, answer the concerns below.


1. Observe the reactions in the video, and also then rank the alkaline earth metals from most to the very least reactive through water.

2. What explains the differences in reactivity?

3. Guess the reactivity of beryllium through water. Wherein would it fit in her ranking?

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


1. What room alkaline planet metals? What room their physical properties?

2. Why space alkaline planet metals really reactive?

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

Noble Gases

Characteristics of team 18 the the routine table.

· identify the noblegases.

· perform properties of noblegases.

· define the nonreactivity the noblegasesand how it is concerned theoctet rule.


Okay, helium balloons space light, yet they’re no that light! This fanciful picture serves to do the suggest that helium is among the lightestelements. Helium belongs come a group of elements called the noble gases.

What are Noble Gases?

Noble gasesare nonreactive, nonmetallicelementsin team 18 that the regular table. Together you can see in the routine table inFigurebelow, noble gases incorporate helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and also radon (Rn). All noble gases space colorless and odorless. They also have lowboilingpoints, explaining why they room gases in ~ roomtemperature. Radon, at the bottom of the group, is radioactive, so it constantly decays come otherelements. For an excellent overview of the noble gases, clock the video at this URL:


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

· come explore details noble gases, click their symbols in the periodic table at this URL:http://www.ptable.com/.


Q:Based on their position in the periodic table (Figureabove), how numerous valenceelectronsdo friend think noble gases have?

A:The number of valenceelectronsstarts in ~ one for elements 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 eight valence electrons.

Chemical nature of Noble Gases

Noble gases are the the very least reactive of all known elements. That’s because with eight valenceelectrons, their outer energy levels space full. The only exemption is helium, which has actually just 2 electrons. Yet helium also has a complete outerenergy level, due to the fact that its only energy level (energy level 1) deserve to hold a maximum of 2 electrons. A full outer energy level is the most stable arrangement of electrons. As a result, noble gases cannot become more stable by reacting with other elements and gaining or shedding valence electrons. Therefore, noble gases are rarely associated inchemical reactionsand practically never formcompoundswith other elements.

Noble Gases and also theOctet Rule

Because the noble gases space the the very least reactive of every elements, your eight valence electrons are offered as the standard for nonreactivity and also to describe how other facets interact. This is declared as the octet (“group of eight”) rule. According to this rule,atomsreact to formcompoundsthat enable them to have a team of eight valence electrons prefer the noble gases. For example, sodium (with one valence electron) reacts with chlorine (with seven valence electrons) to type the stable compound salt chloride (table salt). In this reaction, sodium donates an electron and chlorine accepts it, giving each aspect an octet that valence electrons.

Some offers of Noble Gases

Did you ever get helium balloons prefer those in the opened picture? uneven a balloon filled with air, a balloon filled through helium needs to it is in weighted down so the won’t float far — although friend don’t have to use one elephant!.

Q:Why go a helium balloon float far if it’s not weighted down?

A:Heliumatomshave just twoprotons, twoneutrons, and also two electrons, so they have actually less massive than any other atoms other than 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 irradiate bulbs, prefer the one pictured in theFigurebelow, didn’t last very long. The filaments quickly melted out. Although air was pumped the end of the bulb, the wasn’t a finish vacuum. Oxygen in the small amount of air remaining inside the light pear reacted with the steel filament. This corroded the filament and also caused dark store on the glass. Pour it until it is full a light bulb with argon gas prevents these problems. That’s why contemporary light bulbs space filled with argon.

Q:How walk argon stop the problems of beforehand light bulbs?

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


Noble gases are also used to to fill the glass tube of lighted indicators like the one in theFigurebelow. Return noble gases room chemically nonreactive, your electrons deserve to be energized by sending out anelectric currentthrough them. As soon as this happens, the electrons jump to a higherenergy level. When the electrons go back to their original energy level, they give off energy as light. Various noble gases give off irradiate of different colors. Neon gives off reddish-orange light, prefer the word “Open” in the authorize below. Krypton offers off violet light and also xenon gives off blue light.



· Noble gases space nonreactive, nonmetallic aspects in group 18 that the routine table.

· Noble gases room the least reactive of all elements. That’s because they have eight valence electrons, which fill their outerenergy level. This is the many stable plan of electrons, for this reason noble gases rarely react with various other elements and formcompounds.

· Theoctet rulestates thatatomsreact to form compounds that permit them to have actually eight valence electrons favor the noble gases, which are the the very least reactive elements.

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

Explore More

Watch the video about noble gases in ~ the following URL, and then prize the inquiries below.


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

2. Compare the thickness of these noble gases come the density of air.

3. Explain how the mass of noble gases transforms from the optimal to the bottom of group 18.


1. What room noble gases?

2. Explain why noble gases space almost totally nonreactive.

See more: Convert 52 Degrees Fahrenheit To Celsius ), 52 F To C (52 Fahrenheit To Celsius)

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

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