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An atom is the smallest particle of an element still having the same chemical properties of the element.
See the fact file below for more information on the atom or alternatively, you can download our 26-page Atom worksheet pack to utilise within the classroom or home environment.
Key Facts & Information
EARLY UNDERSTANDING OF THE ATOM
- In Ancient Greece, a man named Democritus figured out that every single thing in the universe must be made up of tiny particles that can’t be divided any further.
- He called these particles “atoms”, which means “uncuttable” in Greek.
- According to him, all matter consists of atoms, which are bits of matter too small to be seen, with an empty space between them.
- He added that atoms are completely solid and have no internal structure but differ in size, weight, and shape depending on their substance.
- However, the Greeks used mathematics and reason, not observations of nature, measurements, tests, or experiments.
- With the emergence of experimental science between the 15th and 18th centuries, however, scientists began to understand the foundation of atomic chemistry.
THE ATOMIC MODELS
- In 1803, English chemist John Dalton started to develop a more scientific definition of the atom. His theory stated that atoms are indivisible, those of a given element are identical, and compounds are combinations of different types of atoms.
- English physicist Joseph John Thomson discovered that atoms are not indivisible, but they had smaller parts.
- He concluded that the atom was composed of electrons scattered throughout a spherical cloud of positive charge.
- In 1911, Rutherford probed an atomic structure by firing positively charged alpha particles at a thin sheet of gold foil. Most passed through with little deflection, but some deflected at large angles. This was only possible if the atom had space.
- He concluded that the positive charge was not spread throughout the atom. It is concentrated in a small, dense center called the nucleus, and the rest is empty space.
- Bohr modified Rutherford’s model by stating that electrons move around the nucleus in orbits of fixed sizes and energies.
- Electron energy on this model was quantized. Electrons could not occupy values of energy between the fixed energy levels.
- Schrodinger stated that electrons do not move in set paths around the nucleus. They behave as waves.
- Also, the location of electrons is not exact. Instead, we have orbitals in which we are more likely to find an electron. His model illustrated the nucleus surrounded by clouds of electron density.
PROPERTIES OF AN ATOM
- The atomic radius of chemical elements is measured by the size of their atoms. Since atomic radii vary predictably across the periodic table, atomic size also varies. For example, the atomic radius of Fluorine (F) is .42, while Neon (Ne) is .38.
- The atom is about 10-10 meters (or 10-8 centimeters) in size. This can be thought of as a rough value for any atom.
- Protons and neutrons have the same mass of about 1.67 × 10-24 grams, defined as one atomic mass unit (amu) or one Dalton.
- Atoms consist of three basic particles: protons, electrons, and neutrons.
- Protons: elementary particle with charge of +1, found in nucleus of atom.
- Neutrons: elementary particle with charge of 0, found in nucleus of atom.
- Atomic number: number of protons in the nucleus of the atom. It defines the chemical properties of the atom.
- Atomic mass: mass of one mole of atoms, in grams, averaged over all stable isotopes. The atom mass of a pure isotope is equal to the number of protons and neutrons. The unit of mass is also called a Dalton (Da).
- Electrons: elementary particle with charge of -1, found outside of the nucleus, in orbitals.
- Generally, the nucleus contains more than 99.9% of the mass of the atom.
- The number of electrons is equal to the number of protons in an atom (Ne = Np). When Ne is not equal to Np (Ne ≠ Np), it is called an ion.
- All the electric forces in an atom’s nucleus are repulsive because the protons repel each other, and the neutrons don’t feel any electric force. If they are held together, nuclear force is generated.
- However, when the nucleus is unstable, it has to get rid of the excess mass or particles through radiation. It continues to be radioactive over the course of time, until it loses enough particles and become stable.
This is a fantastic bundle which includes everything you need to know about the atom across 26 in-depth pages. These are ready-to-use Atom worksheets that are perfect for teaching students about an atom which is the smallest particle of an element still having the same chemical properties of the element.
Complete List Of Included Worksheets
- Atom Facts
- Smallest Things
- Parts of an Atom
- The Atomic Structure
- Fusion – Fission
- Power of an Atom
- Effects of Misuse
- Marie Curie
- Quick Review
- With “Atom”
- Find the Atom
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Link will appear as Atom Facts & Worksheets: https://kidskonnect.com - KidsKonnect, October 1, 2020
Use With Any Curriculum
These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.