Chemistry Atoms, Molecules, and Ions

What are Dalton's four postulates?

- each element is composed of extremely small particles called atoms
- all atoms of a given element are identical to one another, but the atoms of one element are different from the atoms of all other elements
- atoms of an element are not changed into atoms of a different element by chemical reaction
- compounds are formed when more than one element combine; a given compound always has the same relative number and kind of atoms

What is the law of conservation of mass?

mass is neither created nor destroyed

What is the law of constant composition

it states that the composition of a compound never varies no matter the location

Who discovered the law of constant composition?

Joseph Prost

By whom and how was the electron discovered?

J.J Thompson discovered it using the cathode ray experiment

What did J.J Thompson discover during the cathode ray experiment?

the charge to mass ratio of the electon

What was J.J Thompson's model of the atom called? Describe it.

"plum pudding" model, and it featured positive sphere of matter with negative electrons embedded in it

What experiment was used to discover the charge of the electron?

Millikan oil drop experiment

By whom and how was the nucleus discovered?

Rutherford and the gold foil experiment

Describe the atom...

small dense nucleus with protons and neutrons inside, most of the atom is empty space for the electron cloud

Who discovered the proton?

Rutherford

Who discovered the neutron?

Chadwick

Were the neutron and proton discovered at the same time?

no, the neutron was discovered 13 years later

Explain the zyX method of labeling elements

X: symbol, z: mass number, y: atomic number

Define atomic number

protons or electrons in a neutral atom

Define mass number

protons plus neutrons

What is an isotope

atoms of the same element with different masses: differing numbers of neutrons

How are elements arranged on the periodic table?

by increasing atomic ion

What are the rows and columns called on the periodic table?

Rows: periods; columns: groups or families

Which elements have similar chemical and physical properties?

the ones in the same column/family/group

Where are the metals?

left

Where are the non-metals?

right hand side

Where are the metalloids?

the six elements alongside the stair step border

What are the six metalloids?

boron, silicon, geranium, arsenic, antimony, tellurium

What are properties of metals?

good electrical conductors and heat conductors, malleable, ductile, possesses metallic luster, opaque as thin sheets, solid at room temp. (except Hg)

What are properties of non-metals?

poor conductors of heat and electricity, brittle, nonductile, does not possess metallic luster, transparent as thin sheets, solids, liquids, or gases at room temp

What are the five groups with common names on the periodic table, and where are they located?

alkali metals: 1A, alkaline earth metals: 2A, chalcogens: 6A, halogens: 7A, noble gases: 8A

What does a subscript in a chemical formula mean?

the subscript the the right of an element tells the number of atoms of that element in one molecule of the compound

What are the seven diatomic molecules?

H2, N2, O2, F2, Cl2, Br2, I2

What is an empirical formula?

empirical formulas give the lowest whole-number ratio of atoms of each element in a compound

What is a molecular formula?

molecular formulas give the exact number of atoms of each element in a compound

What are structural formulas?

structural formulas show the order in which atoms are bonded

What are perspective drawings?

perspective drawings also show three-dimensional array of atoms in a compound

What is an ion?

a charged particle

What is the charge on a cation?

positive and formed by elements on the left side of the periodic chart

What is the charge on an anion?

negative and are formed by elements on the right side of the periodic chart

How does one show the charge on a transitional metal in the ion name?

roman numerals

What three transition metals can only form one charge?

Ag+1, Cd+2, Zn+2

What are typical endings for polyatomic ions?

-ate, -ite

What are polyatomic ions? Give 2 examples.

a covalent bonded set of two or more atoms, or of a metal complex
- Ammonium NH4 +1
- Hydronium H3O +1