Assigment 1 Flashcards by Sebastian Estrada Padilla

Molecular mass (definition)

It is the sum of the atomic masses of all the atoms in a molecule, expressed in atomic mass units (amu).

amu = g / mol

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Ionic Compound

1 metal (+) and 1 non-metal (-)

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Covalent Compound

2 non-mental (-)

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Ionic Compound with out a transition metal

-Always balance out your charges

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Ionic Compounds With a Transition Metal

Name of transition metal
-Roman Numeral; tell you the charge of the compound
-Nonmetal ending in ide

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Ionic compounds with Polyatomic Atoms

-Name of Metal
-Polyatomic Atom

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Ionic Compounds with a transition Metal & Polyatomic Atoms

-Name of transition Metal
-Roman Numeral
-Polyatomic Atom

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Formula to Name of the Compound(Exp 1)

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Formula to Name of the Compound (Exp 2)

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Prefixes

1- Mono
2-Di
3-Tri
4-Tetra
5-Penta
6-Hexa
7-Hepta
8-Octa
9-Nona
10-Deca

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Covalent Compounds

-Do not balance any of the charges.
-Prefix + Name of nonmetal + Prefix + Nonmetal ending in ide
-Prefix tells you how much of the element there is

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Transition metals (definition)

Elements from 3 - 12 from periodic table. Excellent conductivity, variable oxidation state.

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Isotope (Definition)

It is a variant of a chemical element that has the same number of protons but a different number of neutrons in its nucleus, resulting in the same atomic number but different atomic masses while retaining the same chemical properties

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Average Atomic mass

Average = (mass1percebntage1 + mass2percentage2) / 100

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Determining Atomic Mass by Mass Spectrometry

-Most accurate method for comparing the masses of atoms.
Atoms or molecules are passed into a beam of high-speed electrons and change them to positive ions.
-The amount of the deflection depends on the mass.
-Separates ions by mass-to-charge ratio

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Relative atomic masses of the elements

-Relative scale of atomic masses is based on 12C (12amu)
-Comparison of ratios for two atoms gives ratio of masses.

Relative abundance (definition)

Refers to the proportion of a particular isotope of an element compared to the total amount of all isotopes of that element in a given sample.

Mass spectrum (Problem Steps)

Do exercise
-Divide into light and heavy isotopes
-Remember that relative intensity is = 1

Average atomic mass (formula)

percentage1 * amu1 + percetngae2 *amu2 + … = average atomic mass

The Mole (definition)

-unit of measurement used for counting atoms
-Can relate # of atoms to mass of sample.
-The mass of 1 mole of any element is equal to its atomic mass expressed in grams.
-One mole of anything consists of 6.022137X10^23 units of substance.

Avogadro’s Number

6.022137 X10^23 atoms.

Molar mas or Molecular Weight (definition)

The molar mass of a substance is the mass in g of 1 mole of that substance.
NH3 = N + 3(H) = g / mol

Composition of Compound (definition)

Mass Percentage: the mass of an element in a compound expressed as a % of the total mass of the compound.

Combustion (definition)

Is the chemical process in which a substance reacts with oxygen to produce heat and often light.

Determining the formula of a compound

- Molecular formula (from Mass Spectrometer): exact # of atoms in one molecule of the compound. - Empirical Formula (From Elemental Analyzer): The formula that expresses the smallest whole number ratio of atoms in a compound. Exp. C2 H6 Br2 -> molecular formula. C H3 Br-> empirical formula

Empirical Formula (Determination)

-element analysis: burn the sample in the presence of O2 and determine the % of carbon and hydrogen from the masses of CO2 AND H20 -Calculate # of moles from the elemental masses based on a 100g sample. -Divide each mole by the smallest #

Molecular Formula (Determination)

Note: molar mass must be known. Method 1 -determine empirical formula mass. -determine ratio of molar mass and empirical formula mass. -multiply the # of atoms in the empirical formula by this ratio Method 2 -Calculate the mass of each element in 1 mole of compound -Determine the # of moles of each element per mol of compound. -use integer values from previous step for the molecular formula.

Chemical Equations

Reactants -> Products -Chemical reaction involve rearrangement of atoms. -The total # of atoms is conserved -Change in physical state can occur (solid, liquid, gas, aqueous solution).

Steps for calculating masses of reactants and products

- balance the equation for the reaction. -convert the known mass of reactor or product to moles. -using the equation, use the required mole ratio to calculate the number of moles of the desired reactant or product -convert moles to grams.

Stoichiometric quantities (definition)

Refers to the exact proportion of reactants needed in a chemical reaction so that all reactants are completely consumed with no excess. These quantities are based on the balance chemical equation, which ensures that the law of conservation of mass is followed.

Elemental Compound Composition and stoichiometry

Pendiente

Theoretical Yield (Definition)

This is the maximum amount of product that can be formed from a given amount of reactants, assuming the reaction goes to completion with no losses.

Actual Yield (Definition)

The actual amount of product obtained from the reaction, often measured experimentally.

Percentage Yield (Definition)

Percentage yield is a measure of the efficiency of a reaction, calculated as the ratio of the actual yield and the theoretical yield.

Limiting Reactant ( Definition)

Is the substance that is completely consumed first in a chemical reaction, thus limiting the amount of product that can be formed

Excess reactant (Definition)

Is the substance that is not completely used in a reaction.