L3: The Periodic Table of the Elements Flashcards Preview

Chemistry (Semester 1) > L3: The Periodic Table of the Elements > Flashcards

Flashcards in L3: The Periodic Table of the Elements Deck (12):

What is "the single mass of a single atom; the total mass of the protons, neutrons, and electrons"?

Atomic mass


What is "the total number of protons and neutrons in the nucleus"?

Mass number


What is "the number that identifies an element and is the total number of protons in the nucleus"?

Atomic or proton number


What did Dobereiner theorise?

The law of triads. He noticed a pattern that if you took a certain triad, the average of their collective weights would equal the weight of the middle element.

Cl, Br, I - 35.5, 80, 127
Li, Na, K - 7, 23, 39
Ca, Sr, Ba - 40, 88, 137


Which side of the table is dominated by non-metals?

Right side


What is the formal statement of the Periodic Law?

"Properties of elements are periodic functions of their atomic numbers."


True or false: The most reactive metals are further down the group



True or false: Atoms get smaller further down the group

False. Atoms increase in size down a group


True or false: Metals become more reactive down the group, but non-metals become less reactive



What is an empirical formula?

The simplest ratio of the elements on a molecule.

H2O = H2O
H2O2 = HO
C6H12O6 = CH2O


What are the steps to calculating an empirical formula based on % mass?

1) Write out the % mass of each element
2) Divide the % mass by the element's relative atomic mass
3) Divide each by the smallest number


What are the steps to calculate % composition from a formula? (e.g. find the % of iron in FeSO4.7H2O)

1) Calculate the relative molecular mass by totalling the atomic mass of each constituent atom
2) Divide the Ar of iron by the Mr and times by 100