Subatomic ParticlesSubatomic Particles

Subatomic ParticlesSubatomic Particles

subatomic-lower (or smaller) than an atomsubatomic-lower (or smaller) than an atom Protons-positive particlesProtons-positive particles Neutrons-neutral particlesNeutrons-neutral particles Electrons-negative particlesElectrons-negative particles

Location of particlesLocation of particles Protons and neutrons are in the nucleus Protons and neutrons are in the nucleus

(core) of the atom.(core) of the atom. electrons are buzzing around the nucleus electrons are buzzing around the nucleus

in the electron cloud or shell. in the electron cloud or shell. The The nucleusnucleus makes up 99.99% of the makes up 99.99% of the

massmass of the atom. of the atom. You compared to pocket lintYou compared to pocket lint The The nucleusnucleus is 1/100,000 of the is 1/100,000 of the volumevolume

of an atom of an atom a marble compared to a football stadiuma marble compared to a football stadium

Mass of particlesMass of particles

Since subatomic particles are so small Since subatomic particles are so small they cannot be measured in gramsthey cannot be measured in grams

instead they are measured in atomic mass instead they are measured in atomic mass units or amuunits or amu

1 amu = 1.61x101 amu = 1.61x10-24-24 g g remember 1 g is about the mass of a remember 1 g is about the mass of a

paper clippaper clip

Table of particlesTable of particles

namename symbolsymbol chargecharge locationlocation massmass

protonsprotons pp++ positivepositive nucleusnucleus 1 amu1 amu

neutronsneutrons nnoo neutralneutral nucleusnucleus 1 amu1 amu

electronselectrons ee-- negativenegative electron electron shellshell

.0006 amu.0006 amu

Determining the number Determining the number of subatomic particles in of subatomic particles in

an atoman atom

Determining the number of Determining the number of protonsprotons

Atomic numberAtomic number (the number the periodic (the number the periodic table is arranged by) is the number of table is arranged by) is the number of protons in an atom.protons in an atom.

This number This number cannotcannot change for a given change for a given element without changing the element.element without changing the element.

Oxygen will always have 8 pOxygen will always have 8 p++, He will , He will always have 2 palways have 2 p+.+.

Determining electronsDetermining electrons

If the atom is neutral, the number of If the atom is neutral, the number of protons equal the number of electrons.protons equal the number of electrons.

Therefore copper has 29 eTherefore copper has 29 e--

Krypton has 36 eKrypton has 36 e--

Electrons are the easiest to add or remove Electrons are the easiest to add or remove from an atom.from an atom.

This number can be different from atom to This number can be different from atom to atomatom

IonsIons Charged Particles (atoms that are not Charged Particles (atoms that are not

neutral) neutral) They can be made by changing the They can be made by changing the

number of electrons NOT protons!!number of electrons NOT protons!! SrSr2+2+ or Sr or Sr++++ means strontium with a 2+ means strontium with a 2+

charge on it.charge on it. Strontium with 38 protons and 36 Strontium with 38 protons and 36

electronselectrons OO2-2- or O or O ----

Oxygen with 8 protons and 10 electronsOxygen with 8 protons and 10 electrons

Determining the number of Determining the number of neutrons in an atomneutrons in an atom

The atomic mass number is the number of The atomic mass number is the number of protons + the number of neutrons.protons + the number of neutrons.

mass number – atomic number = # of nmass number – atomic number = # of noo

Aluminum has a mass number of 27 and Aluminum has a mass number of 27 and an atomic number of 13, how many an atomic number of 13, how many neutrons?neutrons?

1414 The number of neutrons is slightly variable The number of neutrons is slightly variable

in a given element.in a given element.

Number of particles in an atomNumber of particles in an atom

carbon has a mass number of 12 and an carbon has a mass number of 12 and an atomic number of 6, how many neutrons, atomic number of 6, how many neutrons, protons and electrons?protons and electrons?

nno o == 6, e6, e-- = 6, p = 6, p+ + = 6= 6 Lithium has a mass number of 7 and an Lithium has a mass number of 7 and an

atomic number of 3 how many neutrons, atomic number of 3 how many neutrons, protons and electrons?protons and electrons?

nno o == 4, e4, e-- = 3, p = 3, p+ + = 3= 3

Number of particles in an atomNumber of particles in an atom

Chlorine has a mass number of 35 and an Chlorine has a mass number of 35 and an atomic number of 17, how many neutrons, atomic number of 17, how many neutrons, protons and electrons?protons and electrons?

nno o == 18, e18, e-- = 17, p = 17, p+ + = 17= 17 Neon has a mass number of 20 and an Neon has a mass number of 20 and an

atomic number of 10 how many neutrons, atomic number of 10 how many neutrons, protons and electrons?protons and electrons?

nno o == 10, e10, e-- = 10, p = 10, p+ + = 10= 10

Number of particles in an ionNumber of particles in an ion IonIon- - charged particle (atom with a different charged particle (atom with a different

number of electrons)number of electrons) ClCl-- mass number- 35mass number- 35

atomic number- 17atomic number- 17 nno o == 18, e18, e-- = 18, p = 18, p+ + = 17= 17 BeBe2+2+ mass number- 9mass number- 9

atomic number- 4atomic number- 4 nno o == 5, e5, e-- = 2, p = 2, p+ + = 4= 4 BB3+3+ mass number- 11mass number- 11

atomic number- 5atomic number- 5 nno o == 6, e6, e-- = 2, p = 2, p+ + = 5= 5

Back to neutrons being slightly Back to neutrons being slightly variablevariable

IsotopeIsotope ~Atoms of the same element with a ~Atoms of the same element with a

different number of neutrons.different number of neutrons. If you grabbed 100 Mg atoms you would If you grabbed 100 Mg atoms you would

find 30 had 13 nfind 30 had 13 noo and 70 had 12 n and 70 had 12 noo.. 70% of the atoms have a mass of 24 amu, 70% of the atoms have a mass of 24 amu,

30% have a mass of 25 amu.30% have a mass of 25 amu.

Decimal Mass numbersDecimal Mass numbers

On the periodic table, mass numbers are On the periodic table, mass numbers are decimals.decimals.

They are averages.They are averages. MgMg 70 x 24 = 168070 x 24 = 1680 30 x 25 = 30 x 25 = 750750 24302430

100=24.3

Another exampleAnother example

CarbonCarbon out of 200 carbon atoms…out of 200 carbon atoms… 199 would have a mass of 12199 would have a mass of 12 1 would have a mass of 141 would have a mass of 14 so the mass number would be…so the mass number would be…

12x 199 = 238814 x 1 = 14____

2402/200 = 12.01 amu

Quick ReviewQuick Review protonsprotons- atomic number =# of p- atomic number =# of p++, this is , this is

the only number that cannot change for an the only number that cannot change for an element.element.

electronselectrons- if the atom is neutral then - if the atom is neutral then # of p # of p++= # of e= # of e--. If it has a charge change . If it has a charge change this number to agree.this number to agree.

neutronsneutrons- mass number – atomic number - mass number – atomic number = # of n= # of noo

Do Do notnot use the use the mass numbermass number from the from the periodic table.periodic table.