Development of the Periodic Table
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Questions and Answers

Which of the following statements is true about halogens?

  • Halogens are typically nonmetal and very reactive. (correct)
  • Halogens exist as monatomic gases.
  • Halogens do not combine readily with other elements.
  • Halogens are good conductors of heat and electricity.

What is the general trend of atomic size in a periodic table?

  • Atomic size increases from left to right within a period.
  • Atomic size remains constant across a period.
  • Atomic size decreases from top to bottom within a group.
  • Atomic size generally increases from top to bottom in a group. (correct)

Which property typically increases from left to right across a period?

  • Melting Point
  • Electron Affinity
  • Ionization Energy (correct)
  • Atomic Size

Which of the following is a characteristic of noble gases?

<p>They are colorless, odorless, and nonflammable under standard conditions. (D)</p> Signup and view all the answers

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

<p>It decreases generally. (C)</p> Signup and view all the answers

How does electronegativity change across a period?

<p>It increases from left to right. (B)</p> Signup and view all the answers

What is the charge of halogens when they exist as ions?

<p>-1 (C)</p> Signup and view all the answers

Which property of elements tends to decrease from top to bottom within a group?

<p>Electron Affinity (C)</p> Signup and view all the answers

What observation did Johann Wolfgang Döbereiner make about groups of three elements?

<p>The middle element's atomic mass was the average of the other two. (B)</p> Signup and view all the answers

What limitation did Döbereiner face with his triads?

<p>He could not arrange all known elements into triads. (B)</p> Signup and view all the answers

What did John Alexander Reina Newlands propose about the arrangement of elements?

<p>Every eighth element exhibits similar properties. (A)</p> Signup and view all the answers

Which statement highlights a limitation of Newlands' Law of Octaves?

<p>It fit only a limited number of known elements at that time. (C)</p> Signup and view all the answers

What was Dmitri Mendeleev's significant contribution to the periodic table?

<p>He organized elements in increasing atomic mass revealing periodic trends. (A)</p> Signup and view all the answers

What did Henry Moseley's experiments reveal about periodic properties?

<p>Atomic number is the organizing factor for periodic properties. (D)</p> Signup and view all the answers

Which element grouping poses a problem for Newlands' Law of Octaves?

<p>Cobalt and nickel. (B)</p> Signup and view all the answers

What insight led to advancements beyond Döbereiner’s and Newlands’ models?

<p>Recurrence of properties is determined by electron configurations. (C)</p> Signup and view all the answers

Which group of elements is known for having a cation charge of +3?

<p>Boron Group (D)</p> Signup and view all the answers

What classification do elements in groups 3 to 12 belong to?

<p>Transition Elements (C)</p> Signup and view all the answers

Which element is NOT considered a metalloid?

<p>Polonium (D)</p> Signup and view all the answers

What is the maximum number of electrons that can occupy the p-block?

<p>6 (D)</p> Signup and view all the answers

Which group of elements is known for having properties that change from nonmetallic to metallic as one moves down the group?

<p>Chalcogens (C)</p> Signup and view all the answers

Which of the following group labels was introduced by IUPAC for standardization?

<p>1 to 18 (C)</p> Signup and view all the answers

Which of the following is a characteristic of the alkali metals?

<p>React vigorously with water (B)</p> Signup and view all the answers

Which block of the periodic table has the highest energy orbitals?

<p>f-block (C)</p> Signup and view all the answers

How many elements does Period 1 of the periodic table contain?

<p>2 (A)</p> Signup and view all the answers

Which of the following describes the electron configuration of 21Sc?

<p>1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p1 (A)</p> Signup and view all the answers

What charge do nitrogen group elements typically acquire when they form ions?

<p>-3 (D)</p> Signup and view all the answers

Which of the following elements is categorized as a noble gas?

<p>Argon (B)</p> Signup and view all the answers

What is the electron charge for elements in group 2 when forming cations?

<p>+2 (A)</p> Signup and view all the answers

Which element(s) is classified as nonmetals?

<p>Hydrogen and Oxygen (D)</p> Signup and view all the answers

What is the primary characteristic of transition metals?

<p>They exhibit high melting and boiling points (D)</p> Signup and view all the answers

Flashcards

Döbereiner's Triads

A grouping of three elements with similar chemical properties, where the middle element's atomic mass is approximately the average of the other two.

Limitations of Döbereiner's Triads

Not all elements could be fit into triads, and sometimes dissimilar elements were grouped together, lacking a consistent pattern.

Law of Octaves

Newlands' observation that elements arranged by increasing atomic mass exhibited similar properties every eighth element.

Limitations of the Law of Octaves

The Law of Octaves only worked well for elements with low atomic masses, and it couldn't account for all elements or predict the existence of noble gases.

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Mendeleev's Periodic Table

A table where elements are arranged by increasing atomic mass, revealing recurring patterns in their properties within rows and columns.

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Periodic Trends

Recurring patterns in the chemical and physical properties of elements as their atomic number increases.

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Moseley's Discovery

The atomic number, not the atomic mass, determines the periodic properties of elements.

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The Periodic Law

The principle stating that the chemical properties of elements are periodic functions of their atomic numbers.

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Halogens

Group 17 elements, highly reactive nonmetals that form diatomic molecules in their elemental state and exist as -1 ions.

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Noble Gases

Group 18 elements, highly stable and typically unreactive, existing as monoatomic gases.

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Atomic Size

The size of an atom, measured by its radius, which is half the distance between the nuclei of two touching atoms.

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Ionization Energy

The energy required to remove an electron from a gaseous atom, indicating the strength of the atom's hold on its outermost electrons.

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Electron Affinity

The energy released when an electron joins a gaseous atom to form an anion, indicating the atom's tendency to gain electrons.

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Electronegativity

The atom's ability to attract electrons towards itself in a chemical bond.

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How does atomic size change down a group?

Atomic size increases as you move down a group because each successive element has an additional energy level, making the atom larger.

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How does ionization energy change across a period?

Ionization energy increases from left to right across a period because the increased nuclear charge attracts electrons more strongly, making them harder to remove.

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Periodic Table

A table that organizes elements based on their atomic number and recurring chemical properties.

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Period

A horizontal row in the periodic table, containing elements with the same number of electron shells.

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Group or Family

A vertical column in the periodic table, containing elements with similar chemical properties.

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Alkali Metals

Elements in Group 1 (excluding hydrogen) that are highly reactive metals, forming +1 cations.

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Alkaline Earth Metals

Elements in Group 2 that are reactive metals, forming +2 cations, less reactive than alkali metals.

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Transition Metals

Elements in Groups 3-12 that are typically shiny, lustrous, and good conductors, with multiple charge states.

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Boron Group

Elements in Group 13 that form +3 cations, including aluminum.

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Carbon Group

Elements in Group 14 that can form chains and branches, with the ability to form a variety of compounds.

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Nitrogen Group

Elements in Group 15 that typically form -3 anions, with intermediate properties between metals and nonmetals.

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Oxygen Group

Elements in Group 16 that form -2 anions, with properties ranging from nonmetallic to metallic.

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Electron Configuration

A notation describing how electrons are distributed in atomic orbitals, using subshells and their electron counts.

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s, p, d, and f-blocks

Sections of the periodic table based on the highest energy orbital of the elements, describing electron configuration.

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Representative Elements

Elements in the s and p-blocks, showing a wide range of properties.

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Study Notes

Development of the Periodic Table

  • Döbereiner's triads (1817): Elements with similar properties grouped in threes. The middle element's atomic mass approximated the average of the lightest and heaviest. Not all elements fitted, and dissimilar elements could be grouped.

  • Newlands' Law of Octaves (1864): Elements with similar properties appeared every eighth element when arranged by increasing atomic mass. Limited to low atomic masses, and needed adjustments for elements like cobalt and nickel. Couldn't explain noble gases.

  • Mendeleev and Meyer: Recognized recurring patterns in element properties when arranged by increasing atomic mass, creating the first modern periodic table. Left gaps for undiscovered elements, predicting their properties.

  • Moseley's contribution: Atomic number, not mass, is the fundamental organizing principle of the periodic table. This principle dictated the periodic law.

Features of the Modern Periodic Table

  • Organization: Arranged by increasing atomic number (with exceptions).

  • Periods: Horizontal rows; properties gradually change across a period.

  • Groups/Families: Vertical columns; elements with similar properties.

  • Group labeling systems: Traditional (Roman numerals & A/B), Arabic numerals & A/B, and IUPAC system (1-18).

  • Specific Groups: Alkali metals (1/1A), alkaline earth metals (2/2A), transition metals (3-12/3B-12B), Boron family (13/3A), Carbon family/Tetrels (14/4A), Nitrogen family/Pnictogens (15/5A), Chalcogens (16/6A), Halogens (17/7A), and Noble gases (18/0)

Classifying the Elements

  • Metals vs. Nonmetals: Left side (excluding Hydrogen) are metals, right side generally nonmetals.

  • Metalloids (Semimetals): Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium (except Polonium), Tennessine.

  • Electron charges: specific elements and their most common charges.

  • s, p, d, and f blocks: Organization based on the highest filled electron orbital.

    • s and p-blocks are called representative elements.
    • d-block are transition metals.
    • f-block are inner transition metals.
    • Number of electrons in each block.

Electron Configuration

  • Describes electron distribution in atomic orbitals.
  • Notation: Atomic subshells (e.g., 1s2, 2s2, 2p6) listed in sequence.
  • Example: 21Sc = 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d1
  • Period Number = highest number in electron configuration.
  • Group number = last subshells in electron configuration.

Group 1 (Alkali Metals):

  • Cations (+1).
  • Soft, lustrous solids.
  • Good conductors.
  • Low densities and melting points.
  • Vigorous reaction with water, producing hydrogen gas and metal hydroxide.

Group 2 (Alkaline Earth Metals):

  • Cations (+2).
  • Harder than alkali metals.
  • Shiny, lustrous.
  • Good conductors.
  • Higher densities and melting points than alkali metals.
  • Reactivity with water decreasing up the group.

Groups 3-12 (Transition Metals):

  • Shiny, lustrous, solid elements.
  • High thermal and electrical conductivity.
  • High melting points.
  • Often exhibiting multiple charge states.

Specific other Groups:

  • Boron Group (13/3A): Intermediate properties. Aluminum common member.
  • Carbon Group (14/4A): Intermediate properties, forming chains and branches.
  • Nitrogen Group (15/5A): Intermediate properties, known to have a common charge-3.
  • Oxygen Group (16/6A): Diverse properties from nonmetal to metal. Common charge -2.
  • Halogens (17/7A): Highly reactive, non-metallic diatomic molecules. (Fluorine most reactive). Poor conductors, low melting and boiling points. Mostly poisonous.
  • Noble Gases (18/0): Monoatomic gases (mostly). Unreactive. Colorless, odorless, nonflammable

  • Atomic Size: Increases down a group, decreases across a period.

  • Ionization Energy: Decreases down, increases across.

  • Electron Affinity: Increases across, decreases down.

  • Electronegativity: Increases across, decreases down.

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Description

Explore the historical progression of the periodic table, from Döbereiner's triads to Moseley's atomic number organization. This quiz covers major contributions and theories that shaped the modern understanding of the elements. Test your knowledge on the evolution of periodic classification and key scientific figures involved.

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