Chemistry Regents Comprehensive Review

Protons

+1 charge; 1 amu; located in the nucleus

Neutron

neutral; 1 amu; located in the nucleus

electron

charge is -1 ; tiny mass; located in orbitals outside the nucleus

Mass number

Protons and neutrons added together, this is the top number in isotopic notation

Atomic number

number of protons, this identifies the element. You can find this on the Periodic Table on your Reference Sheet

Nuclear Charge

number of protons in the nucleus, this makes the nucleus have an overall POSITIVE charge.

How is the periodic table arranged?

Its arranged in order of increasing atomic number

How do you determine the number of neutrons?

Subtract the mass number from the atomic number

Dalton's atomic model

One of the 1st atomic models, atoms were solid, indivisible, spheres

Element

Pure substance, made of one type of atom

Compound

Pure substance; made of two or more different elements in a fixed proportion

Diatomic element

HONClBrIF; still a pure element, two of the SAME element chemically bonded

JJ Thompson

Cathode ray tube, discovered the electron

Rutherford's gold foil experiment lead to the discovery that atoms

were mostly empty space with a small dense positively charged nucleus

Gold Foil Experiment - Most of the alpha particles went straight through the gold foil, this meant

that the atom was MOSTLY EMPTY SPACE

Gold Foil Experiment - Some of the alpha particles were deflected backwards this meant

that the atom has a DENSE POSITIVE NUCLEUS

Bohr's model showed that

the nucleus was small, dense, positive, with electrons that moved in circular orbits around the nucleus

Higher energy levels are

farther from the nucleus and higher in energy

Lower energy levels are

closer to the nucleus, more stable, and lower in energy

Wave mechanical model says that

electrons move in an electron probability cloud around the nucleus

Wave mechanical model says that orbitals are defined as

a region of the most probable electron location

Each atoms is made of a....

positively charged nucleus with orbiting negatively charged electrons on the OUTSIDE

Protons and neutrons are located

IN THE NUCLEUS

In an ATOM the number of protons equals the number of

electrons; the positive charges are cancelled by the negative charges to make a NEUTRAL charge

Average atomic mass is calculated using

natural abundances of isotopes and relative masses of the isotopes

Isotope

same number of protons DIFFERENT number of neutrons

Where do I find polyatomic ions on the reference table?

TABLE E

Ground state

when all electrons are in their lowest possible energy level, with the first orbital having the least amount of energy

Excited state

When an electron gains energy it moves up to a higher energy level

Electrons that move from the ground state to the excited state

electrons must absorb energy to move from a lower energy level to a higher energy level

In terms of electrons, how could an atom emit colored light?

When excited electrons fall to a lower energy level, they can release energy in the form of light

Bright line spectrums can be used to identify elements because

bright line spectra are UNIQUE to every element, this only depends on the element, not amount!

The brightline spectrum is produced when....

excited state release energy and move to lower energy states

Valence electrons

are the outermost electrons; they determine the chemical properties of an atom, can be found in the electron configuration on reference table.

Elements in the same group have similar chemical properties because

elements in the same group have the same number of valence electrons

Why would elements in the same group, like Carbon, Silicon, Germanium all form same number of bonds?

They have the same number of valence electrons and will react in a similar way.

Atoms with a filled valence shell,

are stable; they will not react with other elements

Noble gases do not react because

they have full valence shells and stable electron configurations

Noble gases are located in

group 18! Helium, neon....

STP

Standard temperature and pressure, first page of your reference table on Table A

Atoms of the same element all have the

same number of protons in their nucleus

Nuclear charge is determined by

the number of protons in the nucleus of an atom, you can look at the atomic number on the periodic table

Changing the number of protons in a nucleus...

changing the number of protons in an element will change the identity of the element

Transmutation

when an element changes into a different element

What is evidence that transmutation occurred?

A different element formed

Stability of an isotope depends on

the ratio of protons to neutrons

Most radioactive elements have an atom number of

83 or above!

Table N shows...

each isotope has a specific decay mode and rate of decay (half life)

Table O tells you....

types of particles, mostly in decay, as well as their masses and charges

Alpha Decay

LEAST Penetrating power, and MOST ionizing power and can cause the MOST damage to living tissue; can be stopped by paper, HEAVIEST mass, and positively charged.

Beta Decay

More penetrating power than alpha decay, less ionizing power than alpha, can be stopped by foil, has NO MASS and is negatively charged

Positron decay

Has no mass and is positively charged

Gamma Rays

Highest penetrating power of all of the nuclear decay particles, LEAST ionizing power; can be stopped by lead or thick concrete, has NO MASS and NO CHARGE

Fission reactions

Split a heavy nuclei into smaller ones

Fusion reactions

occur when light nuclei combine into heavier nuclei

In nuclear fission and fusion reactions, mass is converted into

large amounts of energy! Think of nuclear bombs (fission) or the sun (fusion)

Artificial transmutation

requires the bombardment of a nucleus by high energy molecules

Benefits of using radioactive or nuclear reactions are

production of LOTS of energy (nuclear power plant); radioactive dating (determine the age of something)

Risks with radioactive or nuclear reactions can be

biological exposure (cancer poisoning), long term storage, disposal and nuclear accidents

C - 14 isotope is used for

carbon dating of once living organisms

U - 238

geological dating of planets and rocks

I -131

treatment of thyroid disorders

Co - 60

cancer treatments and kill tumors

Atomic Radii Group Trend

how big an atom is, increase as you go down a group because electrons shells are being added

Atomic Radii (Across a Period -> look at table S)

As you move across a period (-->), the atomic radii decreases because the number of protons in the nucleus increases

How does the radius of an ion change when it becomes negative by gaining an electron?

The radius INCREASES

How does the radius of an ion change when it becomes positive by losing electron(s)? Explain in terms of atomic structure

The radius of the ion decreases because an electron shell is lost

Ionization energy

amount of energy required to completely REMOVE an electron

Electronegativity

attraction to an electron within a bond

Where do you find information about atomic radii, ionization energy, electronegativity, density and other properties?

TABLE S

Which element has the strongest attraction to an electron in a bond? Nitrogen or Fluorine? (Use Table S)

Fluorine has the highest electronegativity on table S, indicating it has the strongest attraction to an electron

Name all metalloids

Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium (B, Si, Ge, As, Sb, Te)

Where do you find the metals?

left side of staircase

Where do you find the nonmetals?

Right side of the staircase

Lewis dot diagram

draw valence electrons around an element symbol

Metallic properties

malleable, lusterous, conduct electricity as a solid

Nonmetal properties

dull, brittle, do not conduct electricity

Allotropes of carbon (Like diamond and graphite)

have different structures and different properties (Carbon)

O2 (oxygen) and O3 (ozone) have.....

different structures and different properties (Oxygen)

Breaking a bond is an....

ENDOTHERMIC PROCESS, you must gain energy (bonding)

Forming a chemical bond is an..

EXOTHERMIC PROCESS, you go to a more stable state (bonding)

Ionic bonding

between a METAL and NONMETAL, electrons are transferred here

Atom gains an electron....

it becomes a negative ion with a larger radius ex) F + e- -> F-

Atom loses an electron

it becomes a positive ion with a smaller radius (usually due a loss in a shell) Ex) Na --> Na+ + e-

What are the two categories of compounds?

ionic and molecular (covalent)

(molecular) Covalent bonding

between two nonmetals; electrons are shared

Ionic substance properties

high MP and BP; form crystals, dissolve in water (Table F) and conduct electricity in solution and as a liquid

Ionic substances conduct electricity when dissolved or melted because

ionic substance dissolve into MOBILE FREE MOVING ions. These ions can move freely

Which substance conducts electricity when dissolved or as a liquid but NEVER as solid?

Ionic

Covalent substance properties

never conduct electricity, tend to be soft, low MP and low BP

Metallic bonding

is described as a sea of free moving electrons, resulting in metals being malleable, conductive of electricity and heat

How do you determine if an ionic compound is soluble or insoluble?

USE REFERENCE TABLE F: Solubility guidelines

Polar substances dissolve

only in other polar substances (like dissolves like)

Nonpolar substances dissolve

only in nonpolar substances (like dissolves like)

Single covalent bond has...

1 pair of shared electrons, or 2 electrons being shared

Double covalent bond

2 pair of shared electrons; 4 electrons are being shared total

Triple covalent bond

3 pairs of shared electrons, 6 electrons are being shared in total

How many bonds do these generally form? HONC

H-1; O-2; N-3; C- 4

BOND polarity is determined by

subtracting two electronegativities values, a high difference (0.5 - 1.9999) is POLAR; (0.4 and below) is NONPOLAR

Polar bond forms if

the difference in electronegativity is higher than 0.4