Particles in the Atom : Particles in the Atom Each element is chemically unique. To understand why they are unique,
you need to know the structure of the atom (the smallest particle of an element)
and the characteristics of its components.
Slide 2 :
Particles in the Atom : Electrons
(-) charge no mass located outside the nucleus
Protons
(+) charge 1 amu located inside the nucleus
Neutrons
no charge 1 amu located inside the nucleus Particles in the Atom
Partículas en el átomo : Los electrones
(-) coste no masa situado fuera del núcleo
Protones
(+) coste 1 amu Situado en el interior del núcleo
Neutrones
sin cargo 1 amu Situado en el interior del núcleo Partículas en el átomo
Particles in the Atom : Atoms consist of electrons, protons, and neutrons.
1. Electrons and protons have electrical charges that are identical in magnitude but opposite in sign. Relative charges of ?1 and +1 are assigned to the electron and proton, respectively.
2. Neutrons have approximately the same mass as protons but no charge—they are electrically neutral.
3. The mass of a proton or a neutron is about 1836 times greater than the mass of an electron. Protons and neutrons constitute the bulk of the mass of the atom. Particles in the Atom Copyright 2007 Pearson Benjamin Cummings. All rights reserved.
Discovery of the Neutron : Discovery of the Neutron James Chadwick bombarded beryllium-9 with alpha particles,
carbon-12 atoms were formed, and neutrons were emitted. + Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 764 *Walter Boethe
Humor : Humor Two atoms are walking down the street.
One atom says to the other, “Hey! I think I lost an electron!”
The other says, “Are you sure??”
“Yes, I’m positive!” A neutron walks into a restaurant and orders a couple
of drinks. As she is about to leave, she asks the waiter
how much she owes. The waiter replies, “For you,
No Charge!!!”
Subatomic particles : Subatomic particles Electron Proton Neutron Name Symbol Charge Relative
mass Actual
mass (g) e- p+ no -1 +1 0 1/1840 1 1 9.11 x 10-28 1.67 x 10-24 1.67 x 10-24
Structure of the Atom : Structure of the Atom There are two regions
The nucleus
With protons and neutrons
Positive charge
Almost all the mass
Electron cloud
Most of the volume of an atom
The region where the electron can be found
Subatomic Particles : Subatomic Particles NUCLEUS ELECTRONS PROTONS NEUTRONS Negative Charge Positive
Charge Neutral
Charge ATOM Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Subatomic Particles : Subatomic Particles NUCLEUS ELECTRONS PROTONS NEUTRONS Negative Charge Positive
Charge Neutral
Charge ATOM Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Subatomic Particles : Subatomic Particles Quarks
component of protons & neutrons
6 types 3 quarks = 1 proton or 1 neutron Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Size of an atom : Size of an atom Atoms are incredibly tiny.
Measured in picometers (10-12 meters)
Hydrogen atom, 32 pm radius
Nucleus tiny compared to atom
Radius of the nucleus near 10-15 m.
Density near 1014 g/cm3
IF the atom was the size of a stadium, the nucleus would be the size of a marble. California WEB
Counting the Pieces : Counting the Pieces Atomic Number = number of protons
# of protons determines kind of atom
Atomic Number = number of electrons in a neutral atom
Mass Number = the number of protons + neutrons California WEB 12 6 C Mass Number = A Atomic Number = Z