View
26
Download
0
Category
Preview:
DESCRIPTION
Modern Atom. Basic Structure. Consists of tiny nucleus and the electrons that move about it Nucleus diameter about 10 -13 cm Electron is average distance of 10 -8 cm from the nucleus. Nucleus. Chemistry is mostly about the electrons - PowerPoint PPT Presentation
Citation preview
Modern Atom
Basic Structure
Consists of tiny nucleus and the electrons that move about it
Nucleus diameter about 10-13 cm Electron is average distance of 10-8 cm
from the nucleus
Nucleus
Chemistry is mostly about the electrons Nucleus has a very high density (a lot of
mass and small area)
Nuclear Contents
Protons – positively charged with charge about equal to but opposite of the electrons
Neutrons – no charge and about same mass as protons
What Causes Different Properties
Electrons are the parts that intermingle with other atoms
Different number of electrons (thus protons) causes different interactions and thus different behavior
Atoms Are Very Small In Mass
Hard to express in grams Unit of atomic mass – amu
– 1 amu = 1.66 x 10-24 g
Masses of Subatomic Particles
Proton 1.0073 amu Neutron 1.0087 amu Electron 5.486 x 10-4 amu It takes 1836 electrons to equal the
mass of 1 proton
In General
In a neutral atom the number of protons is equal to the number of electrons
The number of protons determines the identity of the atom
All atoms of the same element have the same number of protons
Isotopes – are atoms of the same element with different numbers of neutrons (thus different masses)
Isotopes are also called Nuclides Atomic mass on the periodic table is the
weighted average of the masses of all naturally occurring isotopes
Ions – atoms with different numbers of protons and electrons
Notation
Mass number shows the total number of protons and neutrons
Atomic number shows the number of protons
Recommended