Name: from atomos to the modern atom
Uploaded: 2023-06-23T15:38:43.000Z
Duration: 1 min 17 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Space Systems

3.3.9-12.C

Atomic Structure

Every element is composed of tiny particles called atoms. These particles give each element distinct physical and chemical properties, such as boiling point, melting point, and density.
All of the atoms of an element have identical properties but differ from those of other elements.
Such differences are due to the subatomic particles&#8212;protons, neutrons, and electrons.
Both protons and neutrons contribute to the atomic mass, with one atomic mass unit each, while electrons have almost negligible mass.
Protons and neutrons are clustered in a central nucleus. The number of protons, equal to the atomic number, determines the specific element.
Protons are positively charged, and neutrons are uncharged, so the nucleus has a net positive charge.
A cloud of negatively charged electrons is attracted to the nucleus. This cloud is mostly empty and makes up most of an atom&#39;s volume.
A neutral atom contains an equal number of protons and electrons, canceling out the positive and negative charges and leading to no net charge.

atomic structure

The Greek philosopher Democritus proposed that everything on Earth is made up of tiny particles called atomos, Greek for &#34;indivisible,&#34; from which the modern term &#34;atom&#34; is derived. In the 19th century, John Dalton proposed the atomic theory that is still largely correct today. He put forth five postulates to explain how atoms made up the world around us. (1) All matter is composed of infinitely small particles or atoms. (2) All atoms of a given element are identical to one another and (3) are different from the atoms of all other elements. (4) Two or more elements can combine in a fixed ratio to form a compound. (5) Atoms cannot be created nor destroyed in a chemical reaction, but can rearrange to form new substances.
Dalton was only partially correct about the particles that make up matter. While atoms cannot be broken down further by ordinary chemical or physical processes, they are composed of three smaller subatomic particles. The first clue about the subatomic structure came when J.J. Thomson discovered the electron. Scientists knew that the overall charge of an atom was neutral, but Thomson&#39;s &#34;plum pudding model&#34; of the atom provided new information regarding the existence of a negatively-charged particle, suggesting that electrons were found studded throughout a positively charged area. Later, Ernest Rutherford performed an experiment showing that most of an atom&#39;s mass is concentrated in the nucleus, where protons account for an atom&#39;s positive charge, and the tiny negatively-charged electrons make up most of the space outside of the nucleus. This disproved Thomson&#39;s plum pudding model. In 1932, James Chadwick discovered that the neutron accounted for the mass present in an atom.
According to the currently accepted theory, protons are found in the nucleus of an atom, have a positive charge, and have a mass of one atomic mass unit (AMU) each. The number of protons equals the atomic number on the periodic table and determines the element&#39;s identity. Neutrons are also found in the nucleus. They have no charge but have the same mass as protons, contributing to an atom&#39;s atomic mass. Electrons orbit around the nucleus in clouds. They have a negative charge and negligible mass, so they contribute to an atom&#39;s overall charge but not its mass.

The Greek philosopher Democritus proposed that everything on Earth is made up of tiny particles called atomos, Greek for &#34;indivisible,&#34; from which ...

Education

JoVE Core

Anatomy and Physiology

Unit 1

Fundamentals of Chemistry

KEY TERMS AND CONCEPTS

from atomos to the modern atom

Atoms are the tiny building blocks of matter, and ideas about them go back to the Greek philosopher Democritus. He suggested that everything on Earth is made of atomos, a Greek word meaning &quot;indivisible.&quot; That idea later led to the modern word atom.

In the 19th century, John Dalton developed an atomic theory that is still largely correct today. He proposed five key ideas. All matter is made of tiny particles called atoms. Atoms of the same element are alike, and atoms of different elements are not. He also said that elements combine in fixed ratios to form compounds, and that atoms are not created or destroyed in a chemical reaction. Instead, they rearrange to make new substances.

Dalton’s model was only partly complete. Atoms cannot be broken down by ordinary chemical or physical processes, but they do contain smaller subatomic particles. The first major clue came from J. J. Thomson, who discovered the electron. At the time, scientists knew atoms were neutral overall, so Thomson’s plum pudding model suggested that negative electrons were spread through a positively charged material.

Later, Ernest Rutherford carried out an experiment that changed the atomic model. His results showed that most of an atom’s mass is packed into a central nucleus. In this model, protons provide the atom’s positive charge, and the tiny negative electrons take up most of the space outside the nucleus. This finding disproved Thomson’s plum pudding model.

In 1932, James Chadwick discovered the neutron, which explained the mass still present in the atom. In the accepted model today, protons and neutrons are in the nucleus. Protons have a positive charge and a mass of one atomic mass unit, or AMU, each. The number of protons equals the atomic number on the periodic table and defines the element. Neutrons have no charge, but they have about the same mass as protons, so they add to atomic mass. Electrons move in clouds around the nucleus. They have a negative charge and very little mass, so they affect the atom’s overall charge more than its mass.

From Atomos to the Modern Atom

what is matter?

Matter, Mass, and Weight Basics

Matter is the substance that makes up the universe, from a grain of sand to a star. Scientists define matter as anything that occupies space and has mass. Mass is the amount of matter in an object, while weight depends on gravity. Mass stays the same whether an object is on Earth or in the zero-gravity environment of outer space. Weight changes when gravity changes. An object weighs more where gravity is stronger and less where gravity is weaker. A piece of cheese that weighs a pound on Earth...

the periodic table and organismal elements

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Organismal Elements in the Periodic Table

The periodic table helps identify the elements that make up living organisms. Biology groups these as organismal elements because they are the chemical building blocks of life. These elements are found in different amounts in the body. Some are present in large quantities, while others are needed only in small amounts. The video connects the periodic table to the elements that organisms actually use. Understanding organismal elements helps students link chemistry to biology. It shows how...

Atoms are the tiny building blocks of matter, and ideas about them go back to the Greek philosopher Democritus. He suggested that everything on Earth is made of atomos, a Greek word meaning "indivisible." That idea later led to the modern word atom. In the 19th century, John Dalton developed an atomic theory that is still largely correct today. He proposed five key ideas. All matter is made of tiny particles called atoms. Atoms of the same element are alike, and atoms of different elements are...

chemical symbols

Chemical Symbols and Element Names

Chemical symbols are short abbreviations that stand for an element or a single atom of that element. Mercury, for example, has the symbol Hg. The same symbol can point to one atom of mercury in the microscopic domain or to a sample labeled as many atoms of mercury in the macroscopic domain. Many symbols come from the element’s common name. Others are shortened from a name in another language. Most chemical symbols use one or two letters. For a few elements with atomic numbers above 112,...

atomic number and mass number

Atomic Identity, Mass, and Isotopes

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atomic weight

Atomic Mass and Mole Calculations

Atomic mass and mole calculations help explain how much matter is in atoms and compounds. Protons and neutrons have about the same mass, about 1.67 × 10 -24 grams. Scientists define that mass as one atomic mass unit, or amu, also called one Dalton. Electrons are much lighter than protons. They weigh only 9.11 × 10 -28 grams, or about 1/1800 of an atomic mass unit. Because of that small mass, electrons do not add much to an element’s overall atomic mass. When chemists calculate atomic mass,...

isotopes and radioisotopes

Radioisotopes in Medicine and Imaging

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electron behavior

Electron Shells and Discovery

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introduction to chemical bonds

How Atoms Bond to Reach Stability

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ionic bonds

Ionic Bonds and Charge Transfer

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covalent bonds

Polar and Nonpolar Covalent Bonds

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hydrogen bonds

Hydrogen Bonding and DNA Stability

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ions, molecules, and compounds

Atomic Charges, Bonds, and Compounds

Atoms can gain or lose electrons during chemical reactions and become ions. An ion is an atom with an electrical charge. This charge is positive or negative, and it often helps the atom reach a full valence shell. Some atoms are more likely to donate electrons, while others are more likely to accept them. Potassium is one example. It has atomic number 19 and one electron in its valence shell, so it is likely to donate that electron and become a slightly positive ion called a cation. Fluorine...

states of matter

Solids, Liquids, Gases, and Plasma

Solids, liquids, gases, and plasma are the main forms of matter described here. Solids are rigid and keep a definite shape. Liquids flow and take the shape of their container, although gravity gives the surface a flat or slightly curved top. Solids and liquids also have volumes that stay nearly the same even when pressure changes. Gases behave differently from solids and liquids. A gas takes both the shape and the volume of its container. In matter with this behavior, the particles are far...

colloids and suspensions

Suspensions, Sedimentation, and Colloids

Suspensions and colloids are two common kinds of mixtures seen in everyday life. Mud and water, flour and water, and tempera paint are suspensions. These mixtures are heterogeneous, which means their particles are not spread out evenly. The particles are relatively large and can be seen with the naked eye or a magnifying glass. Suspension particles make mixtures cloudy, and they settle out after mixing. The settling of particles in a suspension is called sedimentation. A blood test can measure...

introduction to chemical reactions

Chemical Reaction Basics and Equilibrium

Chemical reactions start with reactants and end with products. Reactants are the substances that enter a reaction, and products are the new substances that form. For example, sodium and chloride ions are the reactants in the formation of table salt. Chemical reactions follow the law of conservation of mass. Matter is not created or destroyed during the reaction. That means the atoms and elements in the reactants are still present in the products, and nothing new appears in the products that...

types of chemical reactions: anabolic and catabolic

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Anabolism, Catabolism, and ATP Use

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types of chemical reactions: exchange and reversible

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Electron Transfer and Chemical Equilibrium

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energy transfer in chemical reactions

Chemical Energy and Reaction Types

Chemical reactions depend on energy transfer, chemical bonds, and the way matter collides. A reaction needs enough energy for particles to meet with the right force and precision. That energy can break old bonds and help form new ones. Kinetic energy is the energy of motion. A person lifting a brick uses kinetic energy to move the brick into place on a wall. Once the wall is built, it stores potential energy, which is the energy of position or structure. If the wall falls, that stored energy...

factors influencing the rate of chemical reactions

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Chemical Reaction Rates and Catalysts

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acids, bases and neutralization reactions

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key terms and concepts

Trace how atomic theory developed from Democritus and Dalton to Thomson, Rutherford, and Chadwick, and learn how protons, neutrons, and electrons shape atoms.

From Atomos to the Modern Atom | JoVE K12

anatomy and physiology

JoVE Core Anatomy and Physiology showcases the anatomical and physiological details of the human body in comprehensive, clear, and engaging video animations. This collection of lessons focuses on the structures, components, functions, and requirements of the human body. It is complemented by scientist-in-action videos that demonstrate the application of this knowledge in real-world medical and research settings.

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-1

Next Generation Science Standards

Earth’s Place in the Universe

HS-ESS1-3

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

Matter and Its Interactions

C-PS1-1

C-PS1-2

C-PS1-3.

motion-and-stability-forces-and-interactions

Motion and Stability: Forces and Interactions

C-PS2-6.

Georgia Standards of Excellence

Physical Science

SPS1.

Atomic Structure of atoms

the-principle-of-superposition-and-the-gravitational-field

The Principle of Superposition and the Gravitational Field

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Circular Orbits and Critical Velocity for Satellites

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Kepler's Second Law of Planetary Motion

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Kepler's Third Law of Planetary Motion

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Nuclear Fusion

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Nuclear Fission

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Nuclear Transmutation

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Radioactivity and Nuclear Equations

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Nuclear Stability

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Students who demonstrate understanding can develop a model based on evidence to illustrate the life span of the sun and the role of nuclear fusion in the sun's core to release energy in the form of radiation.  Clarification Statement: Emphasis is on the energy transfer mechanisms that allow energy from nuclear fusion in the sun's core to reach Earth.  Examples of evidence for the model include observations of the masses and lifetimes of other stars, as well as the ways that the sun's radiation varies due to sudden solar flares ("space weather"), the 11-year sunspot cycle, and non-cyclic variations over centuries.  Assessment Boundary: Assessment does not include details of the atomic and sub-atomic processes involved with the sun's nuclear fusion.

3.3.9-12.A

Emission Spectra

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Atomic Spectroscopy: Absorption, Emission, and Fluorescence

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Detection of Black Holes

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The Wave Nature of Light

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Nuclear Binding Energy

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Metal Flame Emission

Metal Flame Emission
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molecular-spectroscopy-absorption-and-emission

Molecular Spectroscopy: Absorption and Emission

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atomic-emission-spectroscopy-instrumentation

Atomic Emission Spectroscopy: Instrumentation

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Atomic Absorption Spectroscopy: Radiation and Light Sources

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Students who demonstrate understanding can construct an explanation of the Big Bang theory based on astronomical evidence of light spectra, motion of distant galaxies, and composition of matter in the universe.  Clarification Statement: Emphasis is on the astronomical evidence of the red shift of light from galaxies as an indication that the universe is currently expanding, the cosmic microwave background as the remnant radiation from the Big Bang, and the observed composition of ordinary matter of the universe, primarily found in stars and interstellar gases (from the spectra of electromagnetic radiation from stars), which matches that predicted by the Big Bang theory (3/4 hydrogen and 1/4 helium).  Assessment Boundary:

3.3.9-12.B

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ultraviolet-and-visible-uvvis-spectroscopy-overview

Ultraviolet and Visible (UV&ndash;Vis) Spectroscopy: Overview

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Atomic Emission Spectroscopy: Lab

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Flame Photometry: Overview

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Tidal Forces

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3.3.9-12.D

From Atomos to the Modern Atom

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