Quick Review Flashcards - Click to flip and test your knowledge!
Question
On what basis did Dobereiner arrange elements into 'triads'?
Answer
Increasing order of atomic weights.
Question
According to Dobereiner, how did the atomic weight of the middle element in a triad relate to the other two?
Answer
It was generally the average of the other two elements' atomic weights.
Question
Newland's 'Law of Octaves' observed that the properties of every eighth element were a repetition of the _____.
Answer
First element.
Question
What was the primary reason for discarding Newland's method of classification?
Answer
It failed to leave spaces for undiscovered elements.
Question
Mendeleev stated that the properties of elements were periodic functions of their _____.
Answer
Atomic weights.
Question
State the 'Modern Periodic Law' as formulated by Moseley.
Answer
Physical and chemical properties of elements are periodic functions of their atomic numbers.
Question
What fundamental property of an atom is equal to its atomic number?
Answer
The number of electrons in the energy shells of a neutral atom.
Question
How are groups numbered in the modern IUPAC notation?
Answer
From 1 to 18.
Question
In the Modern Periodic Table, the horizontal rows are called _____.
Answer
Periods.
Question
What determines the period number of an element in the Periodic Table?
Answer
The number of electron shells in its atom.
Question
Each period (except Period 1) begins with an element having one electron in its outermost shell and ends with a _____.
Answer
Zero group element (noble gas) with a completely filled outer shell.
Question
Which group contains the 'Alkali Metals'?
Answer
Group 1 (IA).
Question
Transition elements are located in which range of groups in the Periodic Table?
Answer
Groups 3 to 12.
Question
What property remains the same for all elements within a single group?
Answer
The number of valence electrons.
Question
How does the number of electron shells change as you move down a group?
Answer
It increases by one at each successive period.
Question
What name is given to the elements of Period 2 that show similarities in properties diagonally with elements of the next group in Period 3?
Answer
Bridge elements.
Question
Identify the element in Period 3 that is a metalloid.
Answer
Silicon ($Si$).
Question
Across a period from left to right, how does the number of valence electrons change?
Answer
It increases by one for each successive element.
Question
Term: Atomic Radius
Answer
Definition: The distance between the centre of the nucleus and the outermost shell of the atom.
Question
What is the common unit used for expressing atomic radii?
Answer
Angstrom unit ($A^{\circ}$).
Question
How does increasing nuclear charge affect the atomic size across a period?
Answer
It decreases the atomic size by pulling the outermost electrons closer to the nucleus.
Question
Down a group, atomic size increases because the effect of the increase in _____ dominates over the increase in nuclear charge.
Answer
Number of electron shells.
Question
Why does Neon ($Ne$) have a larger atomic radius than Fluorine ($F$) despite being further right in the period?
Answer
Its outer shell is completely filled, resulting in a force of repulsion that increases the size.
Question
Term: Ionisation Potential (I.P.)
Answer
Definition: The amount of energy required to remove the most loosely bound electron from the outermost shell of an isolated gaseous atom.
Question
What is the unit of Ionisation Potential?
Answer
Electron volt ($eV$).
Question
How does ionisation potential change across a period from left to right?
Answer
It increases.
Question
Across a period, why does ionisation potential increase?
Answer
Atomic size decreases and nuclear charge increases, binding the outer electrons more firmly.
Question
Down a group, the ionisation potential _____.
Answer
Decreases.
Question
Term: Electron Affinity (E.A.)
Answer
Definition: The amount of energy released when an atom in the gaseous state accepts an electron to form an anion.
Question
Why do noble gases have an electron affinity of zero?
Answer
They have stable electronic configurations and no tendency to accept extra electrons.
Question
Across a period from left to right, how does electron affinity generally trend?
Answer
It increases.
Question
Term: Electronegativity (E.N.)
Answer
Definition: The tendency of an atom to attract the shared pair of electrons towards itself when combined in a compound.
Question
Which element is the most electronegative in the Periodic Table?
Answer
Fluorine ($F$).
Question
Which element is the least electronegative (most electropositive) in the Periodic Table?
Answer
Caesium ($Cs$).
Question
In terms of electron loss or gain, an element is defined as non-metallic if it _____ one or more electrons.
Answer
Gains.
Question
Across a period from left to right, metallic character _____ and non-metallic character increases.
Answer
Decreases.
Question
Why does metallic character increase down a group?
Answer
Atomic size increases and ionisation potential decreases, making it easier for atoms to lose electrons.
Question
What is the nature of the oxides formed by elements on the extreme left of a period?
Answer
Strongly basic.
Question
Across Period 3, the nature of oxides changes from strongly basic to _____.
Answer
Strongly acidic.
Question
What type of chemical bond is formed between two atoms with a large difference in electronegativity?
Answer
Ionic bond.
Question
What type of chemical bond is formed between two atoms with nearly similar electronegativities?
Answer
Covalent bond.
Question
In Group 17 (Halogens), identify the element that is a liquid at room temperature.
Answer
Bromine ($Br$).
Question
Identify the element in Period 3 that forms an amphoteric oxide.
Answer
Aluminium ($Al$).
Question
How does the reducing nature of elements change across a period from left to right?
Answer
It decreases (as oxidising nature increases).
Question
Alkali metals (Group 1) are strong _____ agents because they are electron donors.
Answer
Reducing.
Question
Halogens (Group 17) are strong _____ agents because they are electron acceptors.
Answer
Oxidising.
Question
What happens to the number of electron shells across a period?
Answer
It remains the same.
Question
Why are Noble gases chemically unreactive?
Answer
They have a stable electronic configuration (duplet or octet).
Question
The elements of Group 2 are collectively known as _____ metals.
Answer
Alkaline earth.
Question
How does the valency of elements change across Period 3 with respect to hydrogen?
Answer
It increases from 1 to 4 and then decreases to 1.
Question
Which period in the modern periodic table is the 'shortest' period, containing only two elements?
Answer
Period 1.
Question
In Period 3, which element has the smallest atomic size?
Answer
Chlorine ($Cl$).
Question
What are the two horizontal rows of metals at the bottom of the periodic table called?
Answer
Lanthanide and Actinide series.
Question
What is the electronic configuration of an element in Period 3 and Group 2?
Answer
$2, 8, 2$.
Question
Down Group 17, the physical state of elements changes from gas ($F$, $Cl$) to liquid ($Br$) to _____ ($I$).
Answer
Solid.
Question
What is the valency of elements in the 'Zero Group' (Group 18)?
Answer
Zero.
Question
Which property of an element is considered its 'fundamental property' and forms the basis of the modern classification?
Answer
Atomic number.
Question
Identify the light, soft metals that can be cut with a knife in Group 1.
Answer
Alkali metals (e.g., Sodium, Potassium).
Question
In the context of the Periodic Table, what does 'Periodicity' refer to?
Answer
The recurrence of similar properties of elements at definite intervals.
Question
How does the electronegativity of halogens change as you move from Fluorine to Iodine?
Answer
It decreases.