Atoms & Ions
Electron (e-)
A negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus. The amount of electrons is equal to the atomic number. Electric Charge = -1 Relative Mass = 1/1840 Actual Mass (g) = 9.11 x 10 ^-28
Neutron(n)
A neutral subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton. Electric Charge = 0 Relative Mass = 1 Actual Mass (g) = 1.673 x 10^-24
Neutrons are equal to...
Atomic mass-Atomic Number
Who is this? Contribution to the Atomic Theory: Determines the properties of the nucleus including its charge, mass, and density.
Ernest Rutherford
Why did Ernest Rutherford conclude that the Plum Pudding model was incorrect?
It couldn't explain the Gold Foil Experiment. Calculated that an atom consisted of mostly empty space in which electrons flowed.
Who is this? Contribution to the Atomic Theory: Identifies the electron and determines the mass of an electron to its charge.
JJ Thomson
Who is this? Contribution to the Atomic Theory: 1913, Publishes an atomic theory of atomic structure relating to the electron arrangement in atoms and atomic chemical properties.
Niels Bohr
Which experiment is this? A narrow beam of alpha particles was aimed at a thin sheet of gold foil which produced a flash of light once the particle struck the foil. By noting the flashes, scientists were able to determine the atoms in the gold foil that deflected the alpha particles.
The Gold Foil Experiment by Ernest Rutherford
Which model was proposed to answer why matter is neutral if electrons have a negative charge? It had circles to represent the negative charge, the matter around the electrons contained distributed positive energy.
The Plum Pudding Model
Atom
The smallest particle of an element that retains all the properties of that element. Atoms are electrically neutral, spherically shaped, and composed of subatomic particles.
Ions
an atom or bonded group of atoms with a positive or negative charge.
What are subatomic particles?
protons, neutrons, electrons
Dalton's Atomic Theory
states that: 1. matter is composed of extremely small particles called atoms 2. atoms are indivisible and indestructible 3. atoms of a given element are identical in size, mass, and chemical properties 4. atoms of a specific element are different from those of another element 5. different atoms combine in simple whole-number ratios to form compounds 6. in a chemical reaction, atoms are separated, combined, or rearranged
Protons and electrons are equal to...
the atomic number of the element
