Chemistry: The Periodic Table and Properties

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Questions and Answers

What key relationship did Mendeleeff study to develop the periodic classification of elements?

The relationship between atomic weights and chemical reactivity

The relationship between atomic masses and boiling points

The relationship between atomic weights and valencies (correct)

The relationship between atomic numbers and electron affinity

How many groups and periods are present in the periodic table?

16 groups and 7 periods

20 groups and 8 periods

18 groups and 6 periods

18 groups and 7 periods (correct)

Which block of the periodic table contains elements with valence electrons in the s orbital?

d-block

p-block

s-block (correct)

f-block

Which of the following is NOT a characteristic of metals?

Brittleness Signup and view all the answers

Which position in the periodic table typically exhibits the most non-metallic properties?

Upper right-hand corner Signup and view all the answers

What feature best distinguishes metals from non-metals?

Tendency to form basic oxides Signup and view all the answers

Which noble gas core is used for writing the electronic configuration of Zn?

[Ar] Signup and view all the answers

What is predominantly characteristic of elements in the f-block of the periodic table?

They have valence electrons in the f orbital Signup and view all the answers

What is the primary characteristic of transition elements?

They display variable valencies. Signup and view all the answers

Which of the following statements about ionization energy is true?

Ionization energy is the energy required to remove an electron from a neutral atom. Signup and view all the answers

How is electronegativity defined?

As the tendency of an atom to attract electrons. Signup and view all the answers

What trend is observed in electronegativity as you move across a period?

Electronegativity increases. Signup and view all the answers

What is true about electron affinity?

It is related to the formation of a uni-negative ion. Signup and view all the answers

What is indicated by a negative value of electron affinity?

Energy is released upon adding the electron. Signup and view all the answers

Which element has the highest electronegativity according to Pauling's coefficients?

Fluorine (F) Signup and view all the answers

What happens to ionization energy as you move down a group in the periodic table?

Ionization energy decreases. Signup and view all the answers

What character does the group exhibit as you move down in the periodic table?

Increased metallic character Signup and view all the answers

Which of the following statements about hydrogen is true?

Hydrogen cannot be placed with alkali metals. Signup and view all the answers

Which of the following compounds is considered amphoteric?

Al2O3 Signup and view all the answers

What change occurs to the valency as you move across the periodic table?

The valency varies according to the group Signup and view all the answers

Which of the following describes the position and reactivity of noble gases?

They occupy Group 18 and are mostly unreactive. Signup and view all the answers

What is a significant difference between the first and second members of a group in the periodic table?

The first members differ significantly from the second members. Signup and view all the answers

What happens to noble gases when they form clathrate compounds?

They get trapped in crystal cavities without forming bonds. Signup and view all the answers

How do the acidic properties of oxides change across a period from left to right?

They become more acidic. Signup and view all the answers

Study Notes

Introduction

Mendeleev (1869) proposed elements' properties are periodic functions of their atomic weights, focusing on valencies.
Newlands (1864) observed periodicity but didn't develop it.
Lothar Meyer (1870) provided quantitative proof of atomic property periodicity.

The Periodic Table

Contains 18 groups and 7 periods.
Shows diagonal relationships: Li-Mg, Be-Al, B-Si, C-P.
Divided into four blocks:
- s-block: Valence electrons in s orbital.
- p-block: Valence electrons in s and p orbitals.
- d-block: Valence electrons in s and d orbitals.
- f-block: Valence electrons in s and f orbitals.
Main group elements are in s and p blocks.
Transition elements are in d and f blocks.

Electronic Configurations

Simplified using noble gas cores of preceding periods.
Example: Period 4 elements (K to Br) use Argon core.
- Zn = [Ar]3d104s2

Metals and Non-Metals

Metals: High electrical and thermal conductivities, metallic luster, malleable and ductile.
Non-metals: Lack typical metallic properties.
Distinguishing feature: Metals form basic oxides, non-metals form acidic oxides.
Metals dominate the periodic table: Groups 1, 2, 3, d and f block elements.
Metallic properties increase towards the lower left corner, non-metallic towards the upper right.

Trends Across a Period and Down a Group

Across a period: Gradual change from metallic to non-metallic character.
- Na2O (basic) → MgO (basic) → Al2O3 (amphoteric) → (SiO2)x (acidic) → P4O10 (acidic) → SO3 (acidic) → Cl2O7 (acidic)
Down a group: Metallic character increases.
- N2O3 (acidic) → P4O6 (less acidic) → As4O6 (amphoteric) → Sb4O6 (basic) → Bi2O3 (basic)

Differences Between First and Second Members of a Group

Significant differences between the first and second members of a group.
First members form compounds heavier members don't.
- Example: Lithium differs more from sodium than sodium from potassium.

Valencies of Elements

Main group elements exhibit their group valency or 8 minus group valency.
Transition metals exhibit variable valencies based on their valence electrons.

Position of Hydrogen

Unique element, not readily categorized in any main group.
Does not readily lose its electron like alkali metals.
Does not readily gain an electron like halogens.

Position of Noble Gases

Occupy Group 18/0, implying zero valency.
Heavier members (Kr, Xe) form compounds (fluorides, oxides).
Lighter members (He, Ar) resist chemical reactions.
Form clathrate compounds: Gases trapped in cavities of other compounds, not forming bonds.
Position is interesting: Follows reactive non-metals (halogens), precedes reactive metals (alkali metals).

Transition Elements

Dense metals, high melting points, variable valencies.
Marked catalytic activities.
Colored salts, solid and in solution.
Three rows: 1st, 2nd, 3rd.
Ten groups: Triads or congeners.
f-block contains lanthanides and actinides.

Electronegativity

Tendency of an atom to attract electrons in a compound (Pauling, 1931).
Smaller atoms attract electrons more strongly, higher electronegativity.
Increases across a period and decreases down a group.

Ionization Energy

Energy required to remove an electron from a gaseous atom.
First ionization energy: Removing the first electron.
Second ionization energy: Removing the second electron from a singly charged ion.
Determined spectroscopically.

Electron Affinity

Energy released when an electron is added to a neutral gaseous atom.
Forms a uni-negative ion.
Energy released, has a negative sign.
Determined indirectly using the Born-Haber cycle.

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Description

This quiz covers the historical development of the periodic table, including contributions by Mendeleev, Newlands, and Meyer. It also explores electronic configurations, the classification of elements, and the distinction between metals and non-metals. Test your knowledge of the structure and properties of the periodic table!