Chemistry Week 3 - Discovery of Atoms

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Questions and Answers

Match the following scientists with their respective atomic models:

Dalton = Billiard Ball Model Thomson = Plum Pudding Model Rutherford = Planetary Model Bohr = Model of the Hydrogen Atom

Match the following scientists with their contributions to the organization of elements:

Johann Dobereiner = Triads John Newlands = Octaves Dmitri Mendeleev = Periodic Table Jöns Jacob Berzelius = Elemental Symbols

Match the following atomic model features with their corresponding descriptions:

Billiard Ball Model = Atoms as solid, indivisible spheres Plum Pudding Model = Sphere of positive charge with electrons scattered throughout Planetary Model = Small, dense nucleus surrounded by orbiting electrons Electron Cloud Model = Electrons depicted as a cloud around the nucleus

Match the following scientific laws or concepts with their definitions:

Law of Definite Proportions = Atoms of the same or different elements combine in a fixed, whole number ratio Dobereiner's Law of Triads = Atomic mass of the middle element in a triad is roughly equal to the average of the first and third elements Atomic Number = Number of protons in an atom's nucleus Periodic Law = Properties of elements recur periodically when arranged by atomic number Signup and view all the answers

Match the following terms with their corresponding descriptions:

Element = Pure substance composed of only one type of atom Atom = Smallest unit of an element that retains the element's properties Nucleus = Dense, positively charged center of an atom Electron = Negatively charged particle orbiting the nucleus Signup and view all the answers

Match the following models with their primary characteristics:

Dalton's Model = Simple, indivisible spheres Thomson's Model = Positive sphere with embedded electrons Rutherford's Model = Nucleus with orbiting electrons Bohr's Model = Quantized electron orbits around the nucleus Signup and view all the answers

Match the following events with their significance in the development of our understanding of atoms:

Dalton's Atomic Theory = Established the foundation for modern atomic theory Thomson's Discovery of the Electron = Revealed the existence of subatomic particles Rutherford's Gold Foil Experiment = Demonstrated the existence of the nucleus Bohr's Model = Introduced the concept of quantized energy levels for electrons Signup and view all the answers

Match the following scientists with their primary area of study:

Dalton = Atomic Theory Thomson = Subatomic Particles Rutherford = Nuclear Structure Bohr = Atomic Spectra Signup and view all the answers

Match the scientists with their contributions to the development of the periodic table.

John Newlands = Proposed the Law of Octaves, noting repeating patterns in properties of elements. Dmitri Mendeleev = Arranged elements by increasing atomic weights, considered the Father of the Periodic Table. Henry Moseley = Used spectroscopic data to arrange elements by increasing atomic number. Linus Pauling = Developed a numerical scale of electronegativity for selected representative elements. Signup and view all the answers

Match the terms related to the periodic table with their definitions.

Atomic Number = The number of protons in an atom's nucleus. Law of Octaves = The observation that similar chemical properties occur every eighth element when arranged by atomic mass. Electronegativity = A measure of an atom's ability to attract shared electrons in a chemical bond. Periodic Table = A tabular arrangement of elements based on their atomic numbers and recurring chemical properties. Signup and view all the answers

Match the following statements with their relevant concepts.

The general trend of electronegativity values increases across the periods (i.e. from left to right). = Electronegativity Trend The Z number corresponds to the number of protons. = Atomic Number Every eighth element exhibited similar properties. = Law of Octaves The electronegativity difference on the H-H bond is 0.00. = Electronegativity Difference Calculation Signup and view all the answers

Match the scientific discoveries with the scientists who made them.

Arranging elements by increasing atomic number. = Henry Moseley Developing a numerical scale of electronegativity. = Linus Pauling Proposing the Law of Octaves. = John Newlands Arranging elements by increasing atomic weights. = Dmitri Mendeleev Signup and view all the answers

Match the following elements with their respective electronegativity values.

H = 2.20 Cl = 3.16 O = 3.44 N = 3.04 Signup and view all the answers

Match the following bonds with their electronegativity differences.

H-Cl = 0.96 C-O = 0.89 P-Cl = 0.61 Al-Ge = 0.24 Signup and view all the answers

Match the following pairs of elements with their electronegativity difference.

Dy-Ta = 1.31 Sc-Sb = 0.84 Lu-Hf = 0.11 Sr-Sn = 0.40 Signup and view all the answers

Match the following scientists with their contributions to atomic theory:

John Dalton = First scientific theory of atoms Antoine Lavoisier = Law of Conservation of Mass Leucippus and Democritus = Matter is composed of atoms John Dalton's theory = Atoms can combine in fixed ratios Signup and view all the answers

Match the following terms with their definitions:

Law of Definite Proportion = Chemical compound formed by elements in fixed mass ratios Law of Multiple Proportions = Ratios of elements in compounds expressed in whole numbers Atoms = Smallest indivisible units of matter Isotopes = Atoms of the same element differing in neutrons Signup and view all the answers

Match the following Dalton's atomic postulates with their statements:

Matter is made up of atoms = Atoms are indivisible Atoms of the same elements have same properties = Homogeneity of elements Atoms cannot be created or destroyed = Conservation of mass Atoms combine in whole number ratios = Fixed ratios in compounds Signup and view all the answers

Match the following laws used by Dalton with their descriptions:

Law of Conservation of Mass = Mass cannot be created or destroyed Law of Definite Proportion = Fixed mass ratios in compounds Law of Multiple Proportions = Multiple combinations of elements Billiard ball model = Representation of atomic structure Signup and view all the answers

Match the following concepts with their implications:

Atoms cannot be created nor destroyed = They can only be rearranged Atoms of different elements = Have different properties Atomic model of Dalton = Simple spherical structure Isotopes = Same element, different neutrons Signup and view all the answers

Match the following atomic theories with their proponents:

John Dalton = Atomic Theory Antoine Lavoisier = Law of Conservation of Mass Leucippus and Democritus = Early atomic ideas Modern Atomic Theory = Combines fixed ratios with isotopes Signup and view all the answers

Match the following chemical principles with their examples:

Law of Definite Proportion = Water always has H2O Law of Multiple Proportions = CO vs CO2 Atom theory = Smallest unit of an element Isotopes = Carbon-12 and Carbon-14 Signup and view all the answers

Match the following elements with their atomic characteristics:

Carbon = Forms compounds with varying ratios Oxygen = Essential for life Hydrogen = Lightest element Neon = Noble gas with full shell Signup and view all the answers

Study Notes

Week 3, 3rd Quarter

This week's material focuses on the discovery of the atom and its structure.

Day 1

Topic: John Dalton and the Concept of Chemical Elements
Key concept: John Dalton proposed a scientific theory of atoms, expanding on the ideas of Leucippus and Democritus.
Dalton's Atomic Theory: Dalton's theory posited that matter consists of indivisible atoms, atoms of the same element share identical properties, and atoms of different elements combine in specific ratios to form compounds.

The Concept of Atoms

Historical development: Leucippus and Democritus initially proposed the existence of atoms as the fundamental building blocks of matter.
Dalton's contributions: John Dalton developed the first modern scientific theory of atoms, establishing a crucial step in understanding matter.
Atomic Model: Dalton's model of an atom was described as a solid sphere, sometimes called the billiard ball model.

Learning Competency

Learning Objective: Students should explain how atomic number led to the synthesis of new elements in the laboratory.
Focus: The atomic number being crucial in identifying new elements, and how experimental synthesis/creation of elements is tied to that understanding.

Learning Objectives

Main ideas in atomic discovery: Understand the core concepts behind the discovery and modeling of the atom's structure and its subatomic constituents.
John Dalton's contributions: Analyze John Dalton's role in shaping the understanding of chemical elements.
Dalton's Theory's role in discovery: Connect how Dalton's atomic theory influenced subsequent discoveries of other elements.

Atoms

Early atomic idea: Leucippus and Democritus suggested atoms as fundamental units (building blocks) of matter.
Dalton's Scientific Theory: Dalton presented the first scientific atomic theory, expanding on the ancient idea.
Dalton's Atomic Theory: Dalton's theory explains how atoms combine to form compounds.

Dalton's Atomic Model

Billiard ball model: Dalton's initial model portrayed atoms as simple, solid spheres.

Laws used by Dalton

Law of Definite Proportions: Compounds are formed from elements in fixed mass ratios.
Law of Multiple Proportions: If two elements combine in multiple ways, the ratios of the masses of one element that combine with a fixed mass of the other element are in the ratios of small whole numbers.
Importance for Dalton's theory: These laws were crucial for Dalton's atomic theory, supporting the idea of atoms combining in specific ways.

Modern Atomic Theory

Composition of matter: Matter is composed of atoms.
Isotopes: Atoms of the same element can have different numbers of neutrons, resulting in isotopes.

Modern Atomic Theory (continued)

Atom's stability through composition: Atoms are indivisible except under extreme conditions, like radioactive decay.
Combining atoms: Atoms of the same or different elements can combine in whole number ratios to form compounds.

Elements

Elements' structure: Elements are composed of a single type of atom, which have unique properties.
Symbolic representation: Jöns Jacob Berzelius introduced a system of symbols to represent elements.
Organization of elements: Dmitri Mendeleev organized known elements in a periodic table, establishing an organizational framework.

The Atomic Number and the Synthesis of New Elements

Importance of atomic number: The atomic number, representing the number of protons, uniquely identifies an element, leading to element synthesis procedures.
Synthesis methods: Creating new elements in the lab typically involves sophisticated techniques, often using particle accelerators to bombard existing elements.

Scientists Explained the Structure of the Atom

Dalton's Billiard Ball Model: Atoms are solid, unbroken spheres.
Thomson's Plum Pudding Model: A sphere of positive charge with negatively charged electrons scattered throughout.
Rutherford's Planetary Model: Atoms contain a dense, positively charged nucleus with electrons orbiting around it.
Bohr Model: Electrons orbit the nucleus in specific energy levels.
Schrödinger's Electron Cloud Model: Electrons exist in a probability cloud around the nucleus, not fixed orbits.

The Arrangement of the Elements

Dobereiner's Triads: Similar elements grouped in threes based on atomic mass.
Newlands' Octaves: Elements arranged in increasing atomic mass, with every eighth element showing similar properties.
Mendeleev's Periodic Table: Elements arranged by increasing atomic weight and recurrent properties, leaving spaces for undiscovered elements.
Moseley's Periodic Table: Elements arranged by increasing atomic number (number of protons), refining the table's predictions and structure.

Atomic Number

Concept: The atomic number of an element is the number of protons in its nucleus.
Identity: Different atomic numbers mean different elements.

Electronegativity

Definition: Electronegativity is a measure of an atom's ability to attract bonding electrons.
Pauling's scale: Linus Pauling created a numerical scale for electronegativity.

Electronegativity (continued)

Trends in the Periodic Table: Electronegativity generally increases across a period and decreases down a group, with some exceptions.

Electronegativity Difference

Calculations: The calculation involves finding the difference of electronegativity values of the relevant elements in a particular bond or compound.

Studying That Suits You

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Description

Explore the foundational concepts of atomic theory as proposed by John Dalton, Leucippus, and Democritus. This quiz focuses on the development of atomic structure and the pivotal contributions made by these scientists in understanding matter. Test your knowledge of Dalton's Atomic Theory and its implications.