Title: Atoms, Isotopes, and Ions
1Atoms, Isotopes, and Ions
2Atomic Theory
- In 1808 John Dalton proposed atomic theory.
- Daltons theory explained several laws known at
the time. - Law of conservation of matter
- Law of definite proportions
- Law of multiple proportions
3Daltons Atomic Theory (1808)
- Elements are made of tiny particles called atoms.
- Atoms of a given element are identical.
- Atoms of different elements differ from each
other in some fundamental way.
4Daltons Atomic Theory (1808)
- Atoms of one element can join with atoms of other
elements to form compounds. - A given compound is always made of the same
elements combined in the same ways. - Explains the law of multiple proportions and the
law of definite composition.
5Daltons Atomic Theory (1808)
- Atoms are indivisible in chemical reactions.
- Chemical reactions change how atoms are grouped
(bonded) together. - Explains the law of conservation of matter.
6Atomic Theory
- Daltons proposal lead to much research as to the
nature of the atom. - In the late 1800s chemists/physicists determined
that the atom is made up of smaller, subatomic,
particles.
7Atomic Theory - 1910
- 1896, JJ Thomson demonstrated that atoms can
emit negative particles. - Called these particles electrons.
- Since atoms are neutral he also proposed that
they must contain positive particles. - These particles were not fully described/named
until 1919.
8Atomic Theory - 1910
- 1910 Lord Kelvin proposed the plum pudding
model of the atom. - Proposed that electrons were scattered within a
cloud/pudding of positive charge.
9Atomic Theory - 1911
- 1911 an experiment was conducted in Ernest
Rutherfords lab that showed the plum pudding
model to be incorrect. - Experiment was conducted by Geiger and Marsden
and the findings interpreted by Rutherford. - See page 84
10The gold foil experiment
- What they did see board
- What they found see board
- What Rutherford concluded.
11Rutherfords Model of the Atom
- First to propose a nuclear atom.
- Rutherford proposed that
- the atom must have nearly all its mass, and
positive charge, in a central nucleus about
10,000 times smaller than the atom itself. - Most of the atom is empty space and the electrons
are scattered through out this empty space.
12A New Model of the Atom
- Expected based on
- Plum pudding model
- Rutherfords model
- Based on his results
13Subatomic Particles
- Rutherford continued to study the atom and the
positive matter of the atom. - 1919, particle named the proton
- 1932 James Chadwick proposed the existence of a
third subatomic particle, the neutron.
14Subatomic Particles
Subatomic Particle Charge Mass, amu Location in atom
Electron (e-) -1 0 amu Outside of nucleus
Proton (p) 1 1 amu Nucleus
Neutron (n) 0 1 amu Nucleus
15Mass of Subatomic Particles
- Protons and neutrons have the same mass (in the
range of 10 -24 g). - Neutrons are slightly heavier.
- Mass is expressed in amu
- Atomic mass unit (amu) 1/12 the mass of a
carbon-12 atom
16Mass of Subatomic Particles
- The mass of the electron is tiny as compared to
that of the proton and neutron. - Therefore, the electrons mass is considered to
be 0 amu when calculating the mass of an atom.
17Subatomic Particles and the Elements
- Each element has a unique number of protons.
- Number of protons defines the element.
18Subatomic Particles and the Elements
- Since atoms are neutral, for every proton there
is a/n _________. - When atoms interact to form compounds, it is
their ___________ that intermingle.
19Terms
- Atomic number number of protons in an atom
- Also indicates the number of electrons in the
atom. - Finding atomic number on the periodic table.
20Terms
- Mass number sum of the of protons and the
neutrons in the nucleus of an atom - FOR MOST ELEMENTS THE MASS NUMBER IF NOT ON THE
PERIODIC TABLE. - You will be given enough information to determine
mass number or number of neutrons.
21Terms
- Isotopes atoms of a given element that differ
in mass number - Isotopes have the same number of _____________.
- Isotopes differ in the number of _______.
22Isotopes
- Writing atomic symbols for isotopes
- See board and pg 87
23FAQ - Isotopes
- When is mass number found on the periodic table?
- Whats the atomic mass? Is it the same as the
mass number?
24Practice
25Ion Formation
- Ions are formed when atoms gain or lose
electrons. - Proton and neutron number are unchanged when an
ion forms.
26Ions - Terms
- Ion charged atom or group of atoms
- Cation positively charged ion
- Metals form cations.
- Anion negatively charged ion
- Nonmetals form anions.
27Ions
- Na atom
- _____ protons _____ electrons
- Na ion
- _____ protons _____ electrons
- Name of ion sodium ion
28Ions
- Calcium atom
- _____ protons _____ electrons
- Ca 2 ion
- _____ protons _____ electrons
- Name of ion calcium ion
29Ions
- Sulfur atom
- _____ protons _____ electrons
- S2- ion
- _____ protons _____ electrons
- Name of ion sulfide ion
30Ion Charge and the Periodic Table
Group Ion Charge e- lost/gained
I A 1 1 e- lost
II A 2 2 e- lost
III A metals 3 3 e- lost
V A nonmetals 3- 3 e- gained
VI A nonmetals 2- 2 e- gained
VII A 1- 1 e- gained
31Naming Ions
- Name of a monatomic cation is the name of the
element - Examples
- Ca 2 calcium ion
- Al 3 aluminum ion
- K
32Naming Ions
- Monatomic anions are named by changing end of the
name of the element to ide - Example S2- sulfide ion
33Naming Ions
- You need to know
- N3- nitride ion
- P3- phosphide ion
- O2- oxide ion
- S2- sulfide ion
- F- fluoride ion
- Cl - chloride ion
- Br- bromide ion
- I- iodide ion
34Ionic Compounds
- Structure
- In an ionic compound there is a regular
arrangement of oppositely charged particles. - Ions are arranged in a 3-D crystalline structure
that maximizes attractive forces and minimizes
repulsive forces. - Also called a lattice structure
- See page 102
35Ionic Compounds
- Physical Properties all are related to the
structure of the compounds - Solids at room temperature
- Relatively high melting and boiling points
- No vapor pressure
- Meaning they dont evaporate
- Electrolytes
- Conduct electricity when melted or dissolved in
water
36Ionic Compounds
- The chemical formula for an ionic compound
represents the lowest, whole number ratio of the
component ions that has a net charge of zero. - Total positive charge total negative charge
37Ionic Compounds
- Name the compound by naming the ions.
38Ionic Compounds
- Writing formulas for and naming binary ionic
compounds - Magnesium oxide
39Ionic Compounds
- Magnesium oxide
- The formula is the simplest ratio of ions that
have a net charge of zero. - Ions present Mg2 and O2-
- Formula
40Ionic Compounds
- Magnesium chloride
- The formula is the simplest ratio of ions that
have a net charge of zero. - Ions present Mg2 and _____
- Formula
41Ionic Compounds
- Practice
- Note we are currently applying the content of
4.11 and 5.2 (type I binary ionic compounds)
42Types I Binary Compounds
- Compound between a metal and a nonmetal
- Metal forms only one ion
- Name the cation and then the anion.
- Name of the cation is the name of the element
- Name of the anion is the name of the nonmetal
with the ending changed to ide
43Monoatomic cations to know
Group Charge on ion examples
IA 1 Na1 sodium (ion) K1 potassium (ion)
IIA 2 Mg2 magnesium (ion)
IIIA metals 3 Al3 aluminum (ion)
44Monoatomic anions to know
Group Charge on ion examples
VA -3 N3- nitride (ion) P3- phosphide (ion)
VIA -2 O2- oxide (ion) S2- sulfide
VIIA -1 F1- fluoride (ion) Cl1- chloride (ion) Br1- bromide (ion) I1- iodide (ion)
45Practice
- Name ? chemical formula
- Chemical formula ? name