Chem 1 Test 1

Includes info on Mathematics in Chemistry, Matter Property, Atomic Theory & Subatomic Particles, Atomic Weight & Mole, Light & Photoelectric Effect, and Quantum Theory

All measurements consist of how many parts?

2

1st Part of Measurement

Numerical value

2nd Part of Measurement

Scalar or unit

1st Thing Numerical Values Reflect

The precision of the instrument used to make the measurement (Quantitatve)

2nd Thing Numerical Values Reflect

the type of data and measurements collected (Qualitative)

qualitative

observations

quantitative

Precision & Accurcay

In Scientific Notation, if the decimal is moved left

The exponent is positive

In Scientific Notation, if the decimal is moved to the right

The exponent is negative

Significant figures (S.F.)

Minimum number of digits needed to write a given values in scientific notation without loss of precision

How many significant figures in 0.0009205?

4

1st Type of Significant Values

Non-zero integers

2nd Type of Significant Values

Captive zeroes

3rd Type of Significant Values

Trailing zeros to the right of a decimal point

What type of trailing zeros are significant?

Trailing zeros to the right of the decimal point

Captive zeroes

A zero that us between 2 non-zero digits in a number

1st Type of Non-significant values

Leading zeroes

2nd Type of Non-significant values

Trailing zeroes to the left of the decimal can be nonsignificant

When are trailing zeroes significant?

Only if the decimal is at the right of the decimal point

When do you round up to find the correct number of SF?

If the number next to it is greater than 5

When do you round down to find the correct number of SF?

If the number next to it is less than 5

When your rounding for correct S.F., what do you do when the number next to it is 5?

You HAVE to round to the nearest even number

During calculations, when do you round?

ONLY at the final answer

For addition or subtraction, what place are answers rounded to?

The fewest number of decimal places

For multiplication or division, what place are answers rounded to?

Number of digits in the number with the fewest S.F.

What is the unit of length?

Meter (m)

What is the unit of mass?

Kilogram (kg)

What is the unit of time?

Second (s)

What is the unit of current?

Ampere (A)

What is the unit of temperature?

Kelvin(K)

What is the unit for amount substance?

Mole (mol)

What is the numerical value in scientific notation of a kilo?

10³

What is the numerical value in scientific notation of a mega?

10^6

What is the numerical value in scientific notation of a centi?

10^-2

What is the numerical value in scientific notation of a milli?

10^-3

What is the numerical value in scientific notation of a micro(µ)?

10^-6

What is the numerical value in scientific notation of a nano?

10^-9

100 cm=

1 m

2.54 cm=

1 in

I mol=

6.02 × 10²³

Accuracy

How close the measurement is to the accepted or “true values”

Precision

How similar/close the measured values are to each other

What is the precison of a measurement dependent on?

The device (i.e.. glassware, tape)

1st Type of Properties

Physical Properties

2nd Type of Properties

Chemical Properties

Physical Properties

characteristic of a substance that you can observe or measure without changing the identity of the substance

Examples of physical properties

Boiling point, density, mass, or volume

Chemical Properites

characteristic of a substance that can only be observed or measured when it undergoes a chemical change

Examples of chemical properties

Flammability, corrosiveness, or reactivity with acid

Density

The relationship between the mass of the substance and how much space it takes up (volume)

1st Type of Changes

Physical Changes

2nd Type of Changes

Chemical Changes

Physical Changes

Changes in matter that DON’T change the composition of a substance

Example of physical changes

Changes of shape, temperature, and volume

Chemical Changes

Result in new substances

Element

A pure substance made of only 1 type of atom

Can elements be broken down?

No

What are example of elements?

Gold (Au), oxygen (O2) and carbon (C)

Compound

Pure substance made of 2 or more elements chemically bonded

How can compounds be broken down?

Only by chemical reaction

What at are examples of compounds?

Water (H2O) and table salt (NaCl)

Homogenous Mixture

Physical combination of substances with a uniform composition throughout, look the same everywhere

Can you see the individual parts of a homogenous mixture?

No

What are homogenous mixtures also called?

Solutions

What are examples of homogenous mixtures?

Salt water, air, and brass

Heterogenous Micture

Physical combination of substances with non-uniform composition throughout

Can you see the layers in heterogenous mixtures?

Yes

Can heterogenous mixtures be seperated?

Yes, physically

What are examples of heterogenous mixtures?

Oil and Water, salad, and and mixed with water

What are the main ways we classify all matter?

Wether they are elements, compounds, homogenous mixtures, or heterogenous

Example of chemical changes

Combustion, oxidation, and decomposition

Dalton’s Atomic Theory of Matter (1803)

The first complete scientific attempt to explain all matter in terms of tiny, indivisible building blocks

1st “Rule” of Dalton’s Atomic Theory

Matter is made of small, discrete, indivisible pieces called atoms.

2nd “Rule” of Dalton’s Atomic Theory

All atoms of an element are identical

3rd “Rule” of Dalton’s Atomic Theory

Atoms combine in small whole-number ratios to form compounds

4th “Rule” of Dalton’s Atomic Theory

Atoms of one element cannot become atoms of another element. Chemical reactions rearrange atoms to form new substances

What does Micheal Faraday’s work suggest?

the electrical nature of matter and the existence of subatomic particles.

How did J.J. Thompson contribute to electron knowledge?

He identified Cathode Rays as electrons and established they carry a negative electrical charge.

What did J.J Thompson and Lord Kelvin propose about a atom?

Atoms are neutral, so the electrons must be suspended in a blob of positive charged “other bits”—plum pudding model

Rutherford’s Gold foil experiment (1911)

Rutherford Geiger and Marsden shoot alpha particles at gold foil and reimagine the inside of atoms as a empty space with dense nucleus

What did the Rutherford Gold foil experiment propose about the arrangement of atoms?

A solar system model

What did Robert Millikan’s work discover?

The mass of electrons and the smallest unit of electric charge

What is the smallest unit of electric charge?

9.107 × 10^-31 kg

1st “Rule” of Atomic Theory

Matter must have large regions of empty space dotted with small regions of very dense matter possessing a positive electrical charge (Proton in the nucleus)

2nd “Rule” of Atomic Theory

The nucleus of an atom is dense and contains most of the mass of the atom

3rd “Rule” of Atomic Theory

Negatively charged electrons surround the nucleus

4th “Rule” of Atomic Theory

positively charged subatomic particle, the PROTON is located in the nucleus.

Atomic Number (Z)

Number of protons or electrons

Mass Number (A)

Number of proton + number of neutrons

how do find the number of neutrons?

Subtract A from Z

Cation

More protons and electrons, giving it a positive charge

Anion

More electrons than protons, giving it a negative charge

Isotopes

atoms of the same element with different masses

Do isotopes have the same number of neutrons?

No

Do isotopes have the same number of protons?

Yes

How are isotopes identified?

By their mass numbers

natural abundance

Percentage of an element that is a particular isotope

Average Mass

Atomic Weight (amu)

When a mass scale on the atomic level is used, what is the base unit?

Atomic Mass Unit (amu)

1 amu =

1.66054 × 10^-24 g