CHEM Test 1

Popular Compound Names

B2H6 Diborane SiH4 Silane NH3 Ammonia PH3 Phosphine H20 Water H2S Hydrogen sulfide

Metalloids

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

Homonuclear diatomic molecules

Both atoms in each molecule are of the same element. Ex: H2, N2, and O2

Some Compounds Named Using Greek Prefixes

CO Carbon Monoxide CO2 Carbon Dioxide SO2 Sulfur Dioxide SO3 Sulfur Trioxide NO2 Nitrogen Dioxide N2O5 Dinitrogen Pentoxide

Group 6A

Chalcogens

Burning wood in a fireplace is a __________ change.

Chemical

Identify this process as a physical or chemical change: Bacteria converts milk to yogurt

Chemical

Nucleus

Quantity center/core of an atom contains protons and neutrons

Physical Change

One in which the state of matter changes, but the identity of the matter does not change. Ex: Melting point, boiling point, freezing point

Chemical Property

One that can be observed and measured by changing the identity of a substance.

Physical property

One that can be observed and measured without changing the identity of a substance.

Melting is a __________ change

Physical

Experiment

Procedure to test hypothesis; measures one variable at a time

Rules for naming acids:

Remove ending of element, Change -ide to end of second element to -ic, Combine two words, Add acid

Nonmetals

Right side

Model (Theory)

Set of conceptual assumptions that explains data from accumulated experiments; predicts related phenomena

Extensive property

The measured value depends on the amount of matter Ex: Mass, length, volume

Intensive property

The measured value does not depends on the amount of matter Ex: Density, temperature

Chemical formula

denotes the composition of the substance.

Heterogeneous mixture

does not have a uniform composition (distinct) Ex: sand and water, water and gasoline

Core electrons

electrons close to nucleus

Groups/Families

vertical columns in the periodic table Elements in the same group tend to have similar physical and chemical properties

Heteronuclear diatomic molecules

A diatomic molecule can also contain atoms of different elements Ex: HCl, H20

Conversion Factor

A fraction in which the same quantity is expressed one way in the numerator and another way in the denominator Conversion factor are equal to 1

Explain the difference between a hypothesis and a theory.

A hypothesis is a tentative explanation for observations made and a theory is a unifying principle that explains a body of experimental observations and the laws that are based on them.

Briefly explain the relationship between hypothesis and experiment in the scientific method.

A hypothesis should be capable of leading to a prediction which is testable by experiment. If the experimental result differs from the prediction, the hypothesis should be modified.

Hypothesis

A tentative explanation that explains observations

Group 8A

Noble/Inert gases

Qualitative

Not requiring explicit measurement a physical property

Inexact numbers

Numbers measured by any method other than counting

Chemical Change

One in which the state of matter changes, and the identity of the matter changes. After a chemical change, the original substance (hydrogen gas in this case) will no longer exist. You get a different substance Ex: combustion

Three physical states

solid, liquid, and gas

Significant Figures in Addition and Subtraction

the answer cannot have more digits to the right of the decimal point than the original number with the smallest number of digits to the right of the decimal point.

Significant Figures in Multiplication and Division

the number of significant figures in the final product or quotient is determined by the original number that has the smallest number of significant figures.

Discuss the difference between the Celsius and Fahrenheit scale for measuring temperatures.

0°C = 32°F and 100°C = 212°F. To convert from °F to °C use the equation °C = (°F -32°F) x 5°C/9°F and to convert from °C to °F use the equation °F = [9°F/5°C](°C) + 32°F

Transition Metals

3B-2B

Group 1A

Alkali Metals (Hydrogen don't count)

Group 2A

Alkaline earth metals

Dimensional Analysis

Also called the factor-label method The use of conversion factors in problem solving

Significant figures Rules

Any digit that is not zero is significant (112.1 has four significant figures). Zeros located between nonzero digits are significant (305 has three significant figures, and 50.08 has four significant figures). Zeros to the left of the first nonzero digit are not significant (0.0023 has two significant figures, and 0.000001 has one significant figure).  Zeros to the right of the last nonzero digit are significant if the number contains a decimal point (1.200 has four significant figures Zeros to the right of the last nonzero digit in a number that does not contain a decimal point may or may not be significant (100 may have one, two, or three significant figures—it is impossible to tell without additional information. To avoid ambiguity in such cases, it is best to express such numbers using scientific notation Ex: 1.3 × 10^2 two significant figures 1.30 × 10^2 three significant figures

Significant figures

Are the meaningful digits in a reported number.

Valence electrons

Electrons far away from nucleus and in outermost shell Roman numeral numbers indicates its valence electrons

Dalton's Atomic Theory

Elements are composed of extremely small particles called atoms. All atoms of a given element are identical, having the same size, mass, and chemical properties. The atoms of one element are different from the atoms of all other elements.  Compounds are composed of atoms of more than one element. In any given compound, the same types of atoms are always present in the same relative numbers. A chemical reaction rearranges atoms in chemical compounds; it does not create or destroy them.

Group 7A

Halogens

A dip of vanilla ice cream is a pure substance.

False

Boiling point and melting point are extensive properties

False

Rusting of a piece of iron under environmental conditions is a physical change.

False

The ripening of fruit, once picked, is an example of physical change

False

When applying the scientific method, it is important to avoid any form of hypothesis

False

Periods

Horizontal rows in the periodic table

Exact numbers

Include numbers with defined values such as: 2.54 in the definition 1 inch (in) = 2.54 cm 1000 in the definition 1 kg = 1000 g 12 in the definition 1 dozen = 12 objects

Atomic mass

Is the mass of an atom in atomic mass units

Neutrons

Neutral charge particles in the nucleus 0

Temperature equations

K= °C +273.15 Temp in Celsius = (temp in F - 32°F) X (5°C/9°F) Temp in Fahrenheit = (9°F/5°C) X (temp in C) + 32°F

Metals

Left side

Base SI Units

Length= meter = m Mass= Kilogram = kg Time= second = s Electric current= ampere = A Temperature= kelvin = K Amount of substance= mole = mol Luminous intensity= candela = cd

Quantitative

Measured and expressed with a number a physical property

Elements are categorized as

Metals, nonmetals, metalloids

Greek Prefixes

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

Observation

Natural phenomena and measured events; if universally consistent can be stated as a law

Electrons

Negatively charged particles in the orbits around the nucleus -1

Accuracy

Tells us how close a measurement is to the true value

Precision

Tells us how close multiple measurements of the same thing are to one another

Prefixes Used with SI Units

Tera- T = 1 x 10^12 Giga- G = 1 x 10^9 Mega- M = 1 x 10^6 Kilo- k = 1 x 10^3 Deci- d = 1 x 10^-1 Centi- c = 1 x 10^-2 Milli- m = 1 x 10^-3 Micro- μ = 1 x 10^-6 Nano- n = 1 x 10^-9 Pico- p = 1 x 10^-12

Further Experiment

Tests predictions based on model

Temperature

The Celsius scale was originally defined using the freezing point (0°C) and the boiling point (100°C) of pure water at sea level. The SI base unit of temperature is the kelvin. Kelvin is known as the absolute temperature scale, meaning that the lowest temperature possible is 0 K, a temperature referred to as "absolute zero."

Proust's law of definite proportions :

The law that describes different samples of a given compound that always contain the same elements in the same mass ratio

Protons

The positively charged particles in the nucleus +1

The density of a substance is an intensive property.

True

The juice from an orange is a mixture.

True

The number 6.0448, rounded to 3 decimal places, becomes 6.045.

True

When applying the scientific method, a model or theory should be based on experimental data.

True

Diatomic molecule

When a molecule contains two atoms Ex: H2O, H2, N2, O2, Cl2, F2, I2, Br2

The law of multiple proportions

When two elements (call them A and B) form two different compounds, the masses of element B that combine with 1 g of element A can be expressed as a ratio of small whole numbers.

Isotopes

atoms that have the same atomic number (Z) but different mass numbers (A).

Binary molecular compounds

consist of just two different elements. To name such a compound, we first name the element that appears first in the formula. We then name the second element, changing the ending of its name to -ide. HCl hydrogen chloride SiC silicon carbide

Homogeneous mixture

has a uniform composition throughout (dissolve) Ex: sugar and water, starch and water

Metalloid

has properties that are intermediate between those of metals and nonmetals

Molecule

is a combination of at least two atoms in a specific arrangement held together by electrostatic forces known as covalent chemical bonds

Mixture

is a combination of two or more substances in which the substances retain their distinct identities. mixtures can be solids, liquids, or gases two types: homogeneous and heterogeneous

Substance

is a form of matter that has a definite (constant) composition and distinct properties. Ex: sodium chloride, iron, water, mercury, carbon dioxide, and oxygen. categorized as either an element or a compound.

Metal

is a good conductor of heat and electricity Ex: Sodium

Mass

is a measure of the amount of matter in an object or sample. 1kg= 1000g = 1 x 10^3 g

Compound

is a substance composed of atoms of two or more elements chemically united in fixed proportions. A compound cannot be separated into simpler substances by any physical process.

Element

is a substance that cannot be separated into simpler substances by chemical means.

Acids

is a substance that produces hydrogen ions (H+) when dissolved in water. Several binary molecular compounds produce hydrogen ions when dissolved in water and are, therefore, acids. In these cases, two different names can be assigned to the same chemical formula Ex: . HCl, hydrogen chloride, is a gaseous compound. When it is dissolved in water, however, we call it hydrochloric acid.

Matter

is anything that has mass and occupies space.

One atomic mass unit (amu)

is defined as a mass exactly equal to one-twelfth the mass of one carbon-12 atom.

Allotrope

is one of two or more distinct forms of an element. Two of the allotropic forms of the element carbon—diamond and graphite—have dramatically different properties.

Atomic weight

is sometimes used to mean average atomic mass. The atomic masses in the periodic table are average atomic masses.

Atomic Number (Z)

is the number of protons in the nucleus of each atom of an element.

Chemistry

is the study of matter and the changes that matter undergoes.

Mass Number (A)

is the total number of neutrons and protons present in the nucleus of an atom of an element. mass number (A) = number of protons (Z) + number of neutrons

Nonmetal

is usually a poor conductor of heat and electricity.

The derived SI unit for volume

meter cubed (m^3)

Density

ratio of mass to volume. d = m/v OR m = vd OR v = m/d 1 g/cm^3 = 1 g/mL = 1000 kg/m^3 1 g/L = 0.001 g/mL

Liquids and gases

referred to collectively as fluids.

Solids and liquids

referred to collectively as the condensed phases.

Structural formula

shows not only the elemental composition, but also the general arrangement of atoms within the molecule.

Molecular formula

shows the exact number of atoms of each element in a molecule