اطلاعات پایه ای در مورد عناصر گروه دوم اصلی

Name: Beryllium
Symbol: Be
Atomic Number: 4
Atomic Mass: 9.012182 amu
Melting Point: 1278.0 °C (1551.15 K, 2332.4 °F)
Boiling Point: 2970.0 °C (3243.15 K, 5378.0 °F)
Number of Protons/Electrons: 4
Number of Neutrons: 5
Classification: Alkaline Earth
Crystal Structure: Hexagonal
Density @ 293 K: 1.8477 g/cm³
Color: gray

 

 

Atomic Structure

Number of Energy Levels: 2   First Energy Level: 2 Second Energy Level: 2

 

Isotopes

Isotope	Half Life
Be-7	53.3 days
Be-9	Stable
Be-10	2600000.0 years

 

Facts

Date of Discovery: 1798
Discoverer: Fredrich Wohler
Name Origin: From the mineral beryl
Uses: spacecraft, missiles, aircraft
Obtained From: beryl, chrysoberyl

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Name: Magnesium
Symbol: Mg
Atomic Number: 12
Atomic Mass: 24.305 amu
Melting Point: 650.0 °C (923.15 K, 1202.0 °F)
Boiling Point: 1107.0 °C (1380.15 K, 2024.6 °F)
Number of Protons/Electrons: 12
Number of Neutrons: 12
Classification: Alkaline Earth
Crystal Structure: Hexagonal
Density @ 293 K: 1.738 g/cm³
Color: grayish

 

 

Atomic Structure

Number of Energy Levels: 3   First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 2

 

Isotopes

Isotope	Half Life
Mg-24	Stable
Mg-25	Stable
Mg-26	Stable
Mg-27	9.45 minutes
Mg-28	21.0 hours

 

Facts

Date of Discovery: 1808
Discoverer: Sir Humphrey Davy
Name Origin: Magnesia (City)
Uses: airplanes, missiles
Obtained From: sea water

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Name: Calcium
Symbol: Ca
Atomic Number: 20
Atomic Mass: 40.078 amu
Melting Point: 839.0 °C (1112.15 K, 1542.2 °F)
Boiling Point: 1484.0 °C (1757.15 K, 2703.2 °F)
Number of Protons/Electrons: 20
Number of Neutrons: 20
Classification: Alkaline Earth
Crystal Structure: Cubic
Density @ 293 K: 1.55 g/cm³
Color: Silvery

 

 

Atomic Structure

Number of Energy Levels: 4   First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 8 Fourth Energy Level: 2

 

Isotopes

Isotope	Half Life
Ca-40	Stable
Ca-41	103000.0 years
Ca-42	Stable
Ca-43	Stable
Ca-44	Stable
Ca-45	162.7 days
Ca-46	Stable
Ca-47	4.5 days
Ca-48	Stable
Ca-49	8.7 minutes

 

Facts

Date of Discovery: 1808
Discoverer: Sir Humphrey Davy
Name Origin: From the latin word calcis (lime)
Uses: life forms for bones and shells
Obtained From: chalk, limestone, marble. 3.5% of crust

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Name: Strontium
Symbol: Sr
Atomic Number: 38
Atomic Mass: 87.62 amu
Melting Point: 769.0 °C (1042.15 K, 1416.2 °F)
Boiling Point: 1384.0 °C (1657.15 K, 2523.2 °F)
Number of Protons/Electrons: 38
Number of Neutrons: 50
Classification: Alkaline Earth
Crystal Structure: Cubic
Density @ 293 K: 2.54 g/cm³
Color: yellowish

 

 

Atomic Structure

Number of Energy Levels: 5   First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 8 Fifth Energy Level: 2

 

Isotopes

Isotope	Half Life
Sr-82	25.36 days
Sr-83	1.35 days
Sr-84	Stable
Sr-85	64.84 days
Sr-85m	1.27 hours
Sr-86	Stable
Sr-87	Stable
Sr-87m	2.8 hours
Sr-88	Stable
Sr-89	50.52 days
Sr-90	29.1 years
Sr-91	9.5 hours
Sr-92	2.71 hours
Sr-93	7.4 minutes

 

Facts

Date of Discovery: 1790
Discoverer: A. Crawford
Name Origin: After Strotian (a Scottish town)
Uses: flares, fireworks, crimson color
Obtained From: celestite, strontianite

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Name: Barium
Symbol: Ba
Atomic Number: 56
Atomic Mass: 137.327 amu
Melting Point: 725.0 °C (998.15 K, 1337.0 °F)
Boiling Point: 1140.0 °C (1413.15 K, 2084.0 °F)
Number of Protons/Electrons: 56
Number of Neutrons: 81
Classification: Alkaline Earth
Crystal Structure: Cubic
Density @ 293 K: 3.51 g/cm³
Color: Silver

 

 

Atomic Structure

Number of Energy Levels: 6   First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 18 Fifth Energy Level: 8 Sixth Energy Level: 2

 

Isotopes

Isotope	Half Life
Ba-130	Stable
Ba-131	11.7 days
Ba-132	Stable
Ba-133	10.5 years
Ba-133m	1.6 days
Ba-134	Stable
Ba-135	Stable
Ba-135m	1.2 days
Ba-136	Stable
Ba-137	Stable
Ba-137m	2.6 minutes
Ba-138	Stable
Ba-139	1.4 hours
Ba-140	12.8 days
Ba-141	18.3 minutes
Ba-142	10.7 minutes

 

Facts

Date of Discovery: 1808
Discoverer: Sir Humphrey Davy
Name Origin: From the Greek word barys (heavy)
Uses: Medical applications, among others
Obtained From: barytine, whiterite

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Name: Radium
Symbol: Ra
Atomic Number: 88
Atomic Mass: (226.0) amu
Melting Point: 700.0 °C (973.15 K, 1292.0 °F)
Boiling Point: 1737.0 °C (2010.15 K, 3158.6 °F)
Number of Protons/Electrons: 88
Number of Neutrons: 138
Classification: Alkaline Earth
Crystal Structure: Cubic
Density @ 293 K: 5.0 g/cm³
Color: silverish

 

 

Atomic Structure

Number of Energy Levels: 7   First Energy Level: 2 Second Energy Level: 8 Third Energy Level: 18 Fourth Energy Level: 32 Fifth Energy Level: 18 Sixth Energy Level: 8 Seventh Energy Level: 2

 

Isotopes

Isotope	Half Life
Ra-222	38.0 seconds
Ra-223	11.43 days
Ra-224	3.66 days
Ra-225	14.9 days
Ra-226	1600.0 years
Ra-228	5.76 years

 

Facts

Date of Discovery: 1898
Discoverer: Pierre and Marie Curie
Name Origin: From the Latin word radius (ray)
Uses: treating cancer
Obtained From: uranium ores