Semester 1 Ahs 131 Lecture Week 1/2

Front 1

Atoms

Back 1

Dalton's Theory
Matter is composed of atoms
Made up of subatomic particles

Front 2

Dalton's Theory

Back 2

John Dalton
1805
Proposed that matter is composed of atoms
Dalton thought atoms were solid indivisible particles
We know now atoms are divisible into subatomic particles

Front 3

Subatomic particles

Back 3

Protons
Neutrons
Electrons

Front 4

Nucleus

Back 4

Protons and Neutrons

Front 5

Protons

Back 5

Located in the nucleus(core)
Mass of 1 atomic unit
Positive charge
Atomic number of an element

Front 6

Neutrons

Back 6

Located in the nucleus(core)
Mass of 1 atomic unit
No charge (neutral)

Front 7

Atomic Mass Weight

Back 7

Number of protons and neutrons

Front 8

Isotopes

Back 8

Different number of neutrons, so different atomic mass weight
Number of protons is always the same for an element
Subtract an atom's atomic number from its mass to get the number of neutrons

Front 9

Hydrogen

Back 9

pict

Front 10

Electrons

Back 10

Negative charge
1/1836th the mass of a proton - almost no mass
Occupy the region outside the nucleus - called the electron cloud

Front 11

Electron Cloud

Back 11

Size of the electron cloud determines the size of the atom
Atomic measurements are in nanometers

Front 12

Electron Cloud
__________________

Energy Levels (Shells)

Back 12

Identified by numbers 1,2,3,4, etc or by letters K,L,M,N
The number of electrons in each shell is 2N squared
First shell 2(1) =2
Second shell 2(2.2) = 8

Front 13

Electron Shells

Back 13

Divided into subshells s, p, d, f by line spectra characteristics

Front 14

s Subshell ("Sharp series)

Back 14

Holds 2 electrons in an atomic orbital
Orbitals can hold a maximum of 2 electrons

Front 15

p Subshell ("principle series)

Back 15

Holds 6 electrons
3 orbitals

Front 16

d Subshell (diffuse series)

Back 16

Holds 10 electrons
5 orbitals

Front 17

f Subshell (fundamental series)

Back 17

Holds 14 electrons
7 orbitals

Front 18

Electron Shells

Back 18

The number of subshells in a shell is equal to the number of the shell
Shell 1 has 1 subshell (s)
Shell 2 has 2 subshells (s, p)
Shells 3 has 3 subshells (s,p,d)

Front 19

Electrons in each shell

Back 19

1 has maximum of 2 electrons
2 has maximum of 8 electrons
3 has maximum of 18 electrons
4 has maximum of 32 electrons
5 has maximum of 50 electrons

Front 20

Filling of subshells

Back 20

After subshell 3, overlaps occur, so 4s fills before 3d; also 5s fills before 4d and 4f

Front 21

Electron Shells

Back 21

Atom is more stable if the outer electron shell is completely filled -
see pic on pg. 7 of handout

Front 22

Electronegativity

Back 22

Positive proton in the nucleus attracts the negatively charged electrons
Electronegativity is the force between an atom's nucleus and electrons

Front 23

Ions

Back 23

An atom's electrons stay with the atom unless a stronger force pulls them away
If you lose an electron, the atom becomes a positive ion

Front 24

Metals

Back 24

Lose electrons
Are electron donors
Become positive ions
Left of periodic table
Cations

Front 25

Non-metals

Back 25

Gain electrons
Electron acceptors
Become negative ions
Anions

Front 26

Polyatomic ion

Back 26

Multiple atoms that work together as a single atom and exhibit a charge
Ex: HCO (bicarbonate)

Front 27

Polyatomic Molecules

Back 27

Have both negative and positive charges
Called Zwitterions
Amino acids

Front 28

Zwitterions

Back 28

Take or give off a H or depending on the pH
Acts as a buffer