chapter 4: the atom p 93 – 101 and 109-112. what is an atom? atoms: makes up all matter makes up...
TRANSCRIPT
Chapter 4: The atomChapter 4: The atom
P 93 – 101 and 109-112P 93 – 101 and 109-112
What is an atom?What is an atom?
Atoms:Atoms: Makes up all matterMakes up all matter Are incredibly smallAre incredibly small Determines the properties of matterDetermines the properties of matter 91 different types of atoms91 different types of atoms 20 synthetic atoms20 synthetic atoms
The atomic theoryThe atomic theory
John Dalton devised a theory of the atom John Dalton devised a theory of the atom in 1808in 1808 Each element is composed of tiny Each element is composed of tiny
indestructible particles called atomsindestructible particles called atoms All atoms of a given element have the same All atoms of a given element have the same
mass and properties that distinguishes them mass and properties that distinguishes them from other atoms/elementsfrom other atoms/elements
Atoms combine in simple, whole number Atoms combine in simple, whole number ratios to form compoundsratios to form compounds
History of the atomHistory of the atom
J.J Thompson (1856 J.J Thompson (1856 – 1940)– 1940) Discovered the Discovered the
electronelectron• Negative chargeNegative charge• Smaller and lighterSmaller and lighter• Assumed to be a Assumed to be a
positive charge within positive charge within the atom to balance the atom to balance electrons: plum electrons: plum pudding modelpudding model
History of the atomHistory of the atom Ernest Rutherford (1909)Ernest Rutherford (1909)
Gold foil experimentGold foil experiment Alpha particles (+ charge) Alpha particles (+ charge)
toward gold foil.toward gold foil. Alpha particles where Alpha particles where
deflected….there must be deflected….there must be a large concentration of + a large concentration of + chargecharge
Came up with nuclear Came up with nuclear theory of the atomtheory of the atom
History of the atomHistory of the atom Nuclear theory of the Nuclear theory of the
atomatom Most of the atoms mass Most of the atoms mass
and positive charge is in and positive charge is in the nucleusthe nucleus
Most of the volume of Most of the volume of the atom is empty space the atom is empty space where tiny electrons sitwhere tiny electrons sit
There are as many + There are as many + charges as – charges so charges as – charges so the atom is neutralthe atom is neutral
Conclusions:Conclusions: The nucleus contains The nucleus contains
Protons (+) and Protons (+) and neutrons (neutral)neutrons (neutral)
The nucleus makes up The nucleus makes up 99.9% of the mass of 99.9% of the mass of the atomthe atom
The electrons are The electrons are present in a cloud present in a cloud surrounding the surrounding the nucleusnucleus
Atomic mass/atomic numberAtomic mass/atomic number
What are the 3 subatomic particles?What are the 3 subatomic particles? Which of the subatomic particles identifies Which of the subatomic particles identifies
an element? an element? PROTONS! Each element has a different PROTONS! Each element has a different
number of protons, thus making it unique.number of protons, thus making it unique. Atomic Number: the # of protons in the Atomic Number: the # of protons in the
nucleus of an atomnucleus of an atom The # of protons is equal to the # of The # of protons is equal to the # of
electrons.electrons. Why?Why?
Atomic Number
Problems:Problems:
How many protons are in Al?How many protons are in Al? 1313
How many protons are in V? How many protons are in V? 2323
How many electrons are in Copper?How many electrons are in Copper? 2929
Mass NumberMass Number
In an atom, where In an atom, where is most of the mass is most of the mass located?located? In the nucleus In the nucleus
What subatomic What subatomic particles are in the particles are in the nucleus? nucleus? Protons & Protons &
NeutronsNeutrons
Mass number is Mass number is the mass found in the mass found in the nucleusthe nucleus mass number: # mass number: #
of protons + # of of protons + # of neutronsneutrons
You can find mass You can find mass number by looking number by looking at the shorthand at the shorthand notation. notation.
Shorthand NotationShorthand Notation Used to show the mass # and atomic number of Used to show the mass # and atomic number of
an element.an element.
14 is the mass #14 is the mass # 7 is the atomic #7 is the atomic # N is the symbol for nitrogenN is the symbol for nitrogen
N147
Shorthand NotationShorthand Notation
Can also be written as: element-mass #Can also be written as: element-mass # Examples Nitrogen-14, Nitrogen-15, Nitrogen-Examples Nitrogen-14, Nitrogen-15, Nitrogen-
1616 How many neutrons are in each of the How many neutrons are in each of the
above elements? above elements? What is the shorthand notation for What is the shorthand notation for
gold-197?gold-197?
Try TheseTry These
What is the mass number of What is the mass number of 4040Ca?Ca? 4040
How many neutrons are in germanium-73?How many neutrons are in germanium-73? 41 41
How many protons, electrons & neutrons How many protons, electrons & neutrons does zinc-65 have? does zinc-65 have? Protons: 30Protons: 30 Electrons: 30Electrons: 30 Neutrons: 35Neutrons: 35
IsotopesIsotopes
Think about pizza…..Think about pizza….. Isotopes are similar forms of the same Isotopes are similar forms of the same
element.element. More specifically, isotopes have the same More specifically, isotopes have the same
number of number of protonsprotons, but different number , but different number of of neutronsneutrons..
If neutrons change, what else changes? If neutrons change, what else changes? MassMass
Atomic MassAtomic Mass
We must take in account all of the We must take in account all of the isotopes in order to get an accurate mass.isotopes in order to get an accurate mass.
The mass on the PT is a weighted The mass on the PT is a weighted average of all the naturally occurring average of all the naturally occurring isotopes of an element.isotopes of an element.
This is called atomic mass. This is called atomic mass.
Carbon IsotopesCarbon Isotopes
Carbon has several isotopesCarbon has several isotopes The two most naturally occurring isotopes The two most naturally occurring isotopes
are carbon-12 and carbon-13 are carbon-12 and carbon-13 This means C-12 and C-13 account for all This means C-12 and C-13 account for all
of the atomic mass. of the atomic mass. So how do we calculate atomic mass? So how do we calculate atomic mass?
Carbon IsotopesCarbon Isotopes
Carbon-12Carbon-12 Mass: 12.000 amuMass: 12.000 amu
(amu: atomic mass (amu: atomic mass unit)unit)
Abundance: 98.89%Abundance: 98.89%
How many neutrons How many neutrons are in carbon-12?are in carbon-12?
Carbon-13Carbon-13 Mass: 13.003 amuMass: 13.003 amu Abundance: 1.11%Abundance: 1.11%
How many neutrons How many neutrons are in carbon-13?are in carbon-13?
Carbon IsotopesCarbon Isotopes
Atomic mass=(mass of isotope 1 x abundance) Atomic mass=(mass of isotope 1 x abundance) + (mass of isotope 2 x abundance) + (mass of + (mass of isotope 2 x abundance) + (mass of isotope 3 x abundance) isotope 3 x abundance)
(12.000 x .9889) + (13.001 x .0111)=12.011 (12.000 x .9889) + (13.001 x .0111)=12.011 amuamu
Find this value on your PT!Find this value on your PT!
Hydrogen IsotopesHydrogen Isotopes
Hydrogen-1Hydrogen-1 Name: protiumName: protium
Hydrogen-2Hydrogen-2 Name: deuterium Name: deuterium
1e
1 p0 n
1e
1 p1 n
Hydrogen IsotopesHydrogen Isotopes
Hydrogen-3Hydrogen-3 Name: tritium Name: tritium
1e
1 p2 n