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Periodic Law (It’s all in the family)

Lara O. and Alex P.

Objective

• Observe similar/unlike properties between elements in the same group

• Observe: density in family 14solubility in family 2 chemical activity in family 1

Introduction to Periodic Law

• Definition- when elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals

ObservationsLithuim water is clear

with the phenolphthalein. Lithium was shiny on the inside and gray on the outside

water with indicator turned pink; the water with Li sizzled and produced hydrogen gas

Sodium water was clear with phenolphthaleinSodium was shiny on the inside

the reaction gave an "explosion”. when Na was placed in water with indicator turned pink. explosion gave off OH gas

Densities of Family 14Lead Tin Silicon

Mass 38.485 g 90.200g 18.465g

Volume 3.5 mL 12.8mL 7.8mL

Density 11 g/mL 7.05 g/mL 2.4 g/mL

Percent error 2.7% 3.2% 3.0%

Solubilities of group 2SO4 -2 CO3 -2 C2O4 -2 CrO4 -2

Mg+2 S I S S

Ca+2 S I I S

Sr+2 I I I S

Ba+2 I I I I

Unknown (Ba+2)

I I I I

Data Analysis and Conclusions

• Dc as amorphous= 1.6 g/cm3• % error of C= 0• Accepted value of density of germanium= 5.46

g/cm3• % error of germanium= 15.85%

Discussion and Conclusions

• Family 1: Alkali GroupTrend: as you go down the group, reactivity increases

Lithium sizzled and gave off H2 gas

Sodium “sparked” and gave off H2 gas

Discussions and Conclusions Cont

• Family 2: Alkaline earth metalsTrend: as you go down the group, solubility decreases

The unknown we tested was Ba+2, we know this because it had the same results

Discussion and Conclusion Cont

• Family 14: Carbon Group• Trend: as you go down the group, density

increases

D=M/V

• As density increases, the mass and volume also increase.

• Mass increases faster.• As you go down a group, shielding/number of

core electron shells increases