The Periodic Table Flashcards
(29 cards)
How did scientists arrange and classify elements before discovering protons, neutrons, electrons?
-by their order of their atomic weight, which we now call its relative atomic mass
-their properties
Why is Dmitri Mendeleev the father of the periodic table?
-he left gaps in his periodic table, for elements yet to be discovered
Who was Dmitri Mendeleev?
-russian chemist who organiesd the known elements
In what year did Mendeleev publish his first periodic table?
1869
How did Mendeleev arrange the elements in his periodic table?
-in order of increasing atomic weights
What two factors did Mendeleev consider when creating his periodic table?
-atomic weights
-properties of the elements and their compounds
What was a notable feature of Mendeleev’s periodic table?
-gaps for undiscovered elements
What did Mendeleev’s arrangement show regarding elements?
-elements with similar chemical properties lined up in groups
What issue arose due to atomic weights in Mendeleev’s table?
-some pairs of elements were in the wrong order
What did Mendeleev do to predict undiscovered elements?
-left gaps and looked at the properties of adjacent elements
How is the modern periodic table arranged?
-in rows (periods), in order of increasing atomic number
-elements with similar properties are arranged in columns (groups)
Why is it called the periodic table?
-elements with similar properties occur at regular intervals
Why did Mendeleev reverse the positions of iodine and tellurium in his periodic table?
-arranged elements by atomic weight
-but tellurium’s heavier isotopes made it appear heavier than iodine, (but iodine has a higher atomic number)
How do isotopes explain tellurium appearing heavier than iodine?
-tellurium has common isotopes like tellurium-128 and tellurium-130
-average atomic mass higher than iodine-127
What did Mendeleev not know when creating his table?
-isotopes, which can affect atomic mass
-led to pair reversals in his arrangement
What is the electronic structure?
-set of numbers to show how the electrons in an atom are arranged in shells
What is the electronic structure?
-first shell two
-rest have 8
The atomic number of sodium is 11. Predict its atomic number
two electrons occupy the first shell
eight electrons occupy the second shell
one electron occupies the third shell
What does the period (row) number on the periodic table indicate about the electronic structure ?
-number of shells
What does the group number (column) on the periodic table indicate about the electronic structure?
-number of electrons in outermost shell
What does the atomic number (top of symbol) on the periodic table indicate about the electronic structure?
-total number of electrons in all shells
The electronic structure of sodium (2,8,1) shows that sodium, Na:
-is in period 3
-is in group 1
-has an atomic number of (2 + 8 + 1) = 11
Metals lose ? to form ??
-electrons
-positive ions
What can we infer when an element does not form positive ions in its reactions?
-it is a non-metal
