The Atom

Elements and Symbols

• C = Carbon• N = Nitrogen• O = Oxygen• Cl = Chlorine• Ba = Barium

• U = ?• Cf = ?• Bk = ?• Md = ?• Es = ?

• K = • Pb =• W =• Sb =

• Co =• Cu =• Cr =• Mg =• Mn =

• Atom: basic unit of matter– Smallest unit of matter that

individually retains the chemical characteristics of an element

– Consists of a dense central region, called a nucleus, surrounded by a negatively charged cloud

– Contains three types of subatomic particles:• Proton• Neutron• Electron

The Proton

• Charge = + 1.602×10−19  C– Called “+1” for clarity

• Located in nucleus of atom• Mass = 1.672 x 10–24 g

– Approx. 1 unified atomic mass unit (u)

– 1 u = 1.66 x 10–24 g• 1/12 the weight of a

Carbon-12 atom

The Neutron

• No charge (0 C)

• Located in nucleus

• Mass = 1.675 x 10–24 g– Approx. = 1 u

The Electron

• Charge = –1.602 x 10–19 C– Called “–1”

• Located outside nucleus in an e- “cloud”

• Mass = 9.109 x 10-28g– Approx. = 0 u

Plum Pudding Model

• J.J. Thomson• 1904

Gold Foil Experiment

• Ernest Rutherford• 1909• Proved J.J. Thomson’s theory

wrong• Evidence for existence of

protons

Evidence of Electrons

Dmitri Mendeleev (1834-1907)

• Russian chemist– Arranged elements in horizontal rows in

order of increasing atomic weight– Started new rows in order to make

columns of chemicals with similar characteristics

– Left spaces open for elements yet to be discovered

Classification of the Periodic TableClassification by Physical Properties

Metals • Shiny• Conduct electricity• Ductile

– Can be drawn through wires

• Malleable (Shapeable)

• High M.P. & B.P• Solids @ room

temp• Except Hg

Non-Metals

• Don’t tend to conduct well

• Not usually ductile

• Tend to be brittle

• Low M.P. & B.P.

• Many are gases at r.t.

Metalloids

• Have chemical characteristics in between those of metals and non-metals

• Includes elements: B (Boron), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), Polonium (Po), Astatine (At)

Classification by Electronic Properties

Alkali Metals

• Group 1 (1A)• Li, Na, K etc.• Soft, shiny metals• Conduct heat and

electricity• React violently with

H2O– Form H2(g) and alkaline

(basic) solutions

Akali(ne) Earth Metals• Group 2 (2A)• Be, Mg, Ca etc.• Not as reactive as Alkali Metals, but still quite

reactive• Tend to make basic solutions when placed in water

Transition Metals

• Groups 3-12• Tend to have high

densities and B.P.• All are metals• Often used for

electrical conduction

• Often have vivid colors when in solution– Used for pigments

Colors of Transition Colors of Transition Metal CompoundsMetal Compounds

Iron Cobalt Nickel Copper Zinc

Lanthanides• Elements 57-71

– Lanthanum (La) to Lutetium (Lu)

• Commonly used in lasers• Can deflect UV and

infrared rays

Actinides/Actinoids

• Elements 89-103– Actinium (Ac) to

Lawrencium (Lr)

• Only Actinium, Thorium (Th), and Uranium (U) occur naturally– Others created by neutron

bombardment

• Radioactive

Groups 13(3A) – 16(6A)

• No common name

• Boundary between metals and non-metals occurs here

• Contain elements abundant in earth’s crust, atmosphere, and living things

• Contains the metalloids

Halogens

• Group 17 (7A)

• Love to form salts with metals– NaCl, KBr, CaCl2

• Like to form diatomic molecules– F2, Cl2, Br2

Noble Gases

• Group 18 (8A)• Very

unreactive• Don’t like to

bond to other molecules

• Generally not abundant

Diatomic Molecules

• Molecules consisting of only two atoms of either the same or different elements– O2

– CO

• Homonuclear Diatomic Molecule: a molecule made of two atoms of the same element– H2

• Heteronuclear Diatomic Molecule: a molecule made of two atoms that are different elements– NO

Dinitrogen (N2)

Allotropism• The existence of multiple pure forms of an

element, in the same phase (solid, liquid, or gas), that differ in structure

• Different forms are called allotropes• Can exhibit varied physical properties and

chemical behaviors• Don’t confuse allotropes with isotopes!!!

O2 O3

• Which atom does the picture below represent?

Atomic #– # of protons

Atomic symbol

Atomic MassAtomic WeightMass #Molar Mass

H C Fe Pd W

Number of Protons

Number of Electrons

Number of Neutrons

Identify the atomic mass, number of protons, and number of neutrons for the following elements.

Isotopes

• Atoms of the same element that have different atomic masses– Same number of protons– Different # of neutrons

Problems1) Lithium has two natural isotopes, 6Li

and 7Li, which have percent abundances of 7.5% and 92.5% respectively. What is the average atomic mass of Lithium?

2) Using the percent abundances below, calculate the average atomic mass for Carbon

• C-12 = 98.890%

• C-13 = 1.110%

• C-14 = 0.0000000001%

3) Antimony (Sb) has two stable isotopes, 121Sb and 123Sb with masses of 120.9038 u and 122.9042 u, respectively. Calculate the percent abundances of these two isotopes

Atomic Orbitals and Electron Configurations

Atomic Orbitals

• Orbital: a specific region in an atom thought to posses the highest probability of containing the electron in question at any one time– Only hold maximum of two electrons at a time– 4 basic types: s, p, d, f

S orbitals• Spherical shape

• Lowest energy of the orbitals

P Orbitals

• Higher energy than s orbitals• Dumb bell shaped• Come in 3’s

• px, py, pz

D Orbitals

• Higher energy than s and p orbitals

• Double dumb bell shape or single dumb bell with a donut

• Come in 5’s

• dxy, dxz, dyz, dx2-y2, dz2

F Orbitals• Higher energy than s, p, and d• Come in 7’s

• How do we know where our electrons are?• Electrons will seek the lowest E orbital available first

Hydrogen

Helium

1

Lithium?

Pauli Exclusion Principle: orbitals may hold up to two electrons. The electrons must be of opposite spin

Hund’s Rule: electrons pair only after each orbital of equal energy is occupied by a single electron

Problems• Determine the electron configurations for the

following atoms1) N2) O3) Ne4) Na5) Mg6) Al7) S8) Fe9) W

Noble Gas Abbreviation

• The electron configuration of the noble gas that precedes the element in question is represented by the noble gas’ bracketed symbol– Example: C = 1s22s22p2 = [He] 2s22p2

• Write the electron configurations for Vanadium and Bismuth

Exceptions to the Rules

• Cr

• Cu

Review Problems1) Which of the following is considered

qualitative data and which is quantitative?a) Temperature

b) Creepiness

2) Juan likes to drive fast. If he regularly speeds along at 160 km/hr, how quickly is he going in miles/hr? In in/s?

3) You have a box that emits a wave that has a wavelength of 5.0 x 10-7 m. Using the electromagnetic spectrum below, predict what comes out of this box.

4) In the Macy's Thanksgiving day parade, 2009, a Smurf made his debut. His white cap contained  36,763 L of helium and it was about 1/10 of his body size. Using this information, calculate the volume of the entire float. If the density of helium is 0.000178 g/cm3, what is the mass of the helium for the entire float in kg? 

5) Identify which of the following are heterogeneous mixtures and which are homogeneous mixtures (solutions)

a) Jim Beam

b) Orange juice

c) Chicken noodle soup

d) 7 up (fresh)

e) Blood

f) Clorox bleach

6) What are the electron configuration and orbital box diagram for Phosphorous?

7) Which element has the chemical symbol Ag?

8) What are the electron configuration and orbital box diagram for Ag?