Chem Lec 1 & 2 Flashcards
What is chemistry?
The study of matter and changes it undergoes
Chemistry encompasses various branches including organic, inorganic, physical, analytical, and biochemistry.
Define matter.
Anything that has mass and occupies space
Matter exists in various states, including solid, liquid, gas, and plasma.
What is distance measured in?
Meters
What is volume measured in?
Liters
What is a graduated cylinder?
A cylinder marked for how much fluid it contains
Used for accurately measuring the volume of liquids.
How should you take a reading from a graduated cylinder?
From the bottom of the meniscus at eye level
This ensures an accurate measurement of the liquid’s volume.
What formula is used to calculate the volume of solids?
Height x Width x Length
This formula applies to regular-shaped solids.
What method is used to find the volume of irregular solids?
Water displacement
The volume of water displaced by the solid indicates its volume.
What is mass is measured in?
Grams
What is density?
Density is the amount of matter in a certain volume.
How do you calculate density?
By measuring the volume and mass of an object and dividing mass by volume.
What are the two temperature scales mentioned?
Celsius and Kelvin
These scales are commonly used in scientific measurements.
What types of thermometers are mentioned?
Digital and liquid
Digital thermometers provide electronic readings, while liquid thermometers use liquid expansion.
When taking temperatures, where should the thermometer bulb be placed?
In the middle of your liquid
This ensures accurate readings by avoiding contact with the container.
True or False: The thermometer bulb should touch the sides or bottom of the container when taking a temperature reading.
False
Touching the sides or bottom can lead to inaccurate temperature measurements.
What is the SI prefix system based on?
Powers of 10
The SI prefix system simplifies the conversion between different units of measurement.
How do you convert to a smaller unit of measurement?
Move the decimal point to the right as many places as the difference in place value.
This method increases the numerical value of the measurement.
How do you convert to a larger unit of measurement?
Move the decimal point to the left as many places as the difference in place value.
This method decreases the numerical value of the measurement.
Fill in the blank: The SI prefix system makes it ______ to convert between units.
easy
What is the freezing point of water in Celsius?
0°C
What is the boiling point of water in Celsius?
100°C
What temperature scale is used in the English system?
Fahrenheit (°F)
What is the absolute temperature scale?
Kelvin (K)
What is the relationship between Celsius and Kelvin?
Units of Celsius and Kelvin are equal in magnitude
In which system is the temperature measured in Celsius?
The Metric system
Fill in the blank: The freezing point of water is ______ in Celsius.
0°C
Fill in the blank: The boiling point of water is ______ in Celsius.
100°C
True or False: The unit of temperature in the SI system is Kelvin.
True
What is accuracy in measurement?
How close a measurement is to the true or accepted value
Accuracy reflects the correctness of a measurement compared to a known standard.
What is precision in measurement?
How closely measurements of the same thing are to one another
Precision indicates the consistency of repeated measurements, regardless of their closeness to the true value.
What are significant figures?
Includes all certain digits and the first uncertain digit
Significant figures are used to convey the precision of measurements.
What are the rules for significant figures regarding non-zero digits?
Non-zero digits are always significant
This principle ensures that all digits except zero contribute to the precision of a measurement.
Are zeros between significant digits considered significant?
Yes, any zeros between two significant digits are significant
This rule applies to maintain the integrity of the measurement’s precision.
In multiplication and division, how is the number of significant figures in the answer determined?
The LEAST number of significant figures in any number of the problem determines the number of significant figures in the answer
This ensures that the answer reflects the precision of the least precise measurement.
When are trailing zeros significant?
A final zero or trailing zeros in the decimal portion ONLY are significant
This rule highlights the importance of decimal placement in determining precision.
In addition and subtraction, what should be counted for significant figures?
Count the number of significant figures in the decimal portion ONLY of each number in the problem
This focuses on the precision of the decimal values involved in the calculation.
What determines the number of significant figures in the final answer for addition and subtraction?
Your final answer may have no more significant figures to the right of the decimal than the LEAST number of significant figures in any number in the problem
This rule ensures the result reflects the least precise measurement in terms of decimal accuracy.
How can 2300 mL be expressed in scientific notation?
2.3 x 10^3 mL
What is the significance of using scientific notation for 2300 mL?
It clarifies the number of significant figures.
True or False: 2300 mL can have either 2, 3, or 4 significant figures.
True
What is Dimensional Analysis?
Problem solving method of chemistry that employs conversion factors
What does Dimensional Analysis do?
Changes one measure to another
What are conversion factors?
Factors used in Dimensional Analysis to convert units
Do all conversion factors have the same significance in terms of significant figures?
No, some have exact (infinite) sig fig while others limit sig figs
Provide an example of a conversion factor with infinite significant figures.
365 days/1 year
Provide an example of a conversion factor that limits significant figures.
1 dime/10 pennies
If a can of Coca-Cola contains 12 fluid ounces, what is the volume in quarts?
0.375 quarts
Calculation: 12 fl oz × (1 qt / 32 fl oz) = 0.375 qt
What is the conversion factor for quarts to fluid ounces?
1 qt = 32 fl oz
What is the conversion factor from centimeters to meters?
100 cm = 1 meter
Convert 12.00 inches to meters.
2.54 cm = 1 in
0.3048 meters
Calculation: 12.00 in * 2.54 cm/in * 1 m/100 cm = 0.3048 m
What is the formula for density?
Density (D) = Mass / Volume
What is the unit of volume in the metric system?
meter cubed (m^3)
What is the relationship between liters and decimeters cubed?
1 liter (L) = 1 decimeter cubed (dm3)
True or False: 1 mL is equal to 1 cm3.
True
If you have 50.00 g of ethanol, what is its volume?
63.4 cm³
Volume can be calculated using the formula: Volume = Mass / Density. Therefore, Volume = 50.00 g / 0.789 g/cm³.
What is the arrangement of particles in a solid?
Particles close together in orderly fashion
Solids have little freedom of motion.
What is the freedom of motion like in solids?
Little freedom of motion
Solids do not conform to the shape of their container.
How do particles behave in a liquid?
Particles close together but not held rigidly in position
This allows particles to move past one another.
What does a liquid do in relation to its container?
Conforms to the shape of the container
Liquids do not have a fixed shape.
Describe the arrangement of particles in a gas.
Particles randomly spread apart
Gases have complete freedom of movement.
What is the freedom of movement like in gases?
Complete freedom of movement
Gases assume both shape and volume of their container.
Fill in the blank: In a solid, particles are _______.
close together in orderly fashion
Fill in the blank: A liquid does not have a fixed shape but _______.
conforms to the shape of the container
True or False: Gases have a definite shape and volume.
False
Gases assume both the shape and volume of their container.
What are the states of matter that can be inter-converted without changing chemical composition?
solid, liquid, gas
What happens to matter when heat is added?
It can change from solid to liquid to gas
What happens to matter when heat is removed?
It can change from gas to liquid to solid
How is matter classified?
As a pure substance or a mixture of substances
Define a mixture.
Group of 2 or more substances that are physically intermingled
What is a key characteristic of mixtures?
They retain many properties of their components
Can mixtures be separated, and if so, how?
Yes, by a physical change
What is a homogeneous mixture?
Composition of the mixture is uniform throughout
Give an example of a homogeneous mixture.
Sugar dissolved in water
What is a heterogeneous mixture?
Composition is not uniform throughout
Give an example of a heterogeneous mixture.
Sugar mixed with iron filings
Fill in the blank: A mixture can vary in its parts by _______.
mass
True or False: A mixture is considered a substance.
False
What can pure substances be classified as?
Either an element or a compound
What characteristics do pure substances have?
A definite (constant) composition and distinct properties
What is an element?
A substance that cannot be broken down further into simpler or other pure substances by physical or chemical means
What does an element consist of?
Only ONE type of atom
What is the periodic table of elements?
A table where each element has a name and is unique because the atoms are unique
How do the properties of compounds compare to those of the elements from which they are formed?
The properties of compounds are ALWAYS different from the properties of the elements
Can an element be separated into simpler substances by chemical means?
No
Give examples of elements.
- Iron
- Mercury
- Oxygen
- Hydrogen
What defines a compound?
Two or more elements chemically combined in definite ratios
Can compounds be separated by physical means?
No
Give examples of compounds.
- Salt
- Water
- Carbon dioxide
What are physical properties?
Can be observed and measured without changing the substance
Examples include color, melting point, states of matter, and density.
Give examples of physical properties.
- Color
- Melting point
- States of matter
- Density
These properties can be measured without altering the substance.
What are physical changes?
Identity of substance stays the same
Examples include changes of state like melting and freezing, and dissolving sugar in water.
What is an example of a physical change?
- Melting
- Freezing
- Dissolving sugar in water
These changes lead to a different form of the same substance.
What are chemical properties?
Determined by chemical changes that are observed
Examples include flammability, acidity, and corrosiveness.
Give examples of chemical properties.
- Flammability
- Acidity
- Corrosiveness
These properties can only be observed during a chemical reaction.
What are chemical changes?
After reaction, original substance no longer exists
Examples include combustion and digestion.
What are indicators of a chemical reaction?
- Color change
- Heat
- Cloudiness
- Bubbles
These indicators signify that a chemical change has occurred.
True or False: Chemical changes lead to a different substance.
True
Chemical changes result in substances that are different from the original.
What is a chemical property?
A characteristic of a substance that describes its ability to undergo chemical changes.
What reaction produces rust?
Iron reacts with oxygen.
What is a defining feature of noble gases?
They are highly unreactive.
What is an example of a chemical change?
Combustion of gas.
What is produced on a metal toy due to chemical changes?
Rust.
What does quantitative data express?
Using numbers.
What does qualitative data express?
Using properties.
What is an extensive property?
A property that depends on the amount of matter.
Provide examples of extensive properties.
- Mass
- Length
What is an intensive property?
A property that does not depend on the amount of matter.
Provide examples of intensive properties.
- Density
- Temperature
- Color
What is the law of conservation of energy?
Energy cannot be created nor destroyed; it can only be converted from one form to another.
This principle is fundamental in physics and implies that the total energy in a closed system remains constant.
What is typically favored in energy states?
Lower energy is typically favored over higher energy.
Lower energy states are associated with greater stability in physical and chemical systems.
What does lower energy indicate in terms of stability?
Lower energy = more stable.
This relationship is important in understanding chemical reactions and physical processes.
What is the law of conservation of mass?
Matter cannot be created nor destroyed.
This law states that the mass of a substance before a chemical change is always equal to the mass of the substance after the change.
In a chemical change, what happens to the mass of substances?
The mass of substance before a chemical change is always equal to the mass of substance after a change.
This principle is critical for balancing chemical equations and understanding stoichiometry.
What is the arrangement criterion for elements in the periodic table?
Elements are arranged according to increasing atomic number
The atomic number represents the number of protons in an atom’s nucleus.
What are periods in the periodic table?
Periods are boxes (elements) in horizontal rows
Each period corresponds to the filling of a different electron shell.
How are periods numbered in the periodic table?
Periods are numbered from top to bottom, but numbers are not usually printed
The absence of printed numbers can lead to confusion regarding the sequence.
What are groups in the periodic table?
Groups are vertical columns called chemical families
Elements in the same group often exhibit similar chemical properties.
How are groups identified in the periodic table?
Groups are identified by 2 rows of numbers across the top of the table (European and US Notations)
These notations help distinguish between different numbering systems used internationally.
True or False: Elements with similar properties are located in horizontal rows.
False
Similar properties are found in vertical columns, not horizontal rows.
What fundamental property leads to the similar behaviors of some elements?
Some elements had similar behaviors which must be due to some fundamental property
This property is often related to their electron configurations.
What is a molecule?
Unit consisting of 2 or more atoms chemically bonded together
Can a molecule consist of the same element?
Yes, a molecule can consist of the same element or different elements
What are diatomic molecules?
Molecules that consist of 2 atoms chemically bonded together
How many elements form diatomic molecules?
7 elements form diatomic molecules
List the 7 diatomic molecules.
- H2
- N2
- O2
- F2
- Cl2
- Br2
- I2
True or False: Some elements behave as single atoms.
False
What are the characteristics of metals?
Shiny, flexible, most are solids, ductile, malleable, good conductors
Mercury (Hg) is a liquid metal.
What does ductile mean in the context of metals?
Able to be drawn into wires
What does malleable mean in the context of metals?
Able to be pounded into thin sheets
Where are metals found on the Periodic Table?
On the left side
What are the characteristics of nonmetals?
Brittle, hard, not ductile, not malleable, poor conductors
Hydrogen (H2) is a nonmetal and is an exception.
Where are nonmetals found on the Periodic Table?
On the right side
What are the characteristics of metalloids?
Have properties of metals and nonmetals, semi-conductors, good and poor conductors
Metalloids are found along the stair-step line on the Periodic Table.
List some examples of metalloids.
- B (boron)
- Si (silicon)
- Ge (germanium)
- As (arsenic)
- Sb (antimony)
- Te (tellurium)
- At (astatine)
