midterm Flashcards
What is the difference between quantitative and qualitative measurements?
Quantitative - measurement without units and numbers; Qualitative - measurement with units and numbers
Example: 10°C is quantitative, while ‘warm’ is qualitative.
Define accuracy in measurement.
How well the measurement is to the exact, known value.
Define precision in measurement.
Repeated similar measurements not necessarily exact.
List the base units for length, mass, and temperature.
- Length - Meter (m)
- Mass - Kilograms (kg)
- Temperature - Kelvin (K)
What is the volume formula for a rectangular object?
V = length x width x height.
What is the density of water?
1 cm³ = 1 mL.
What is scientific notation used for?
To express large or small numbers in a compact form.
Fill in the blank: Water displacement can be calculated using Δ = ______.
final V - initial V.
What are the rules for significant figures?
- All non-zero digits are significant.
- Zeros between non-zero digits are significant.
- Leading zeros are not significant.
- Trailing zeros are significant only if there is a decimal point.
What is the formula for percent error?
% error = |(measured value - accepted value) / accepted value| x 100.
What is a mole (mol)?
Amount of a substance.
At standard temperature and pressure (STP), what volume does 1 mole of gas occupy?
22.4 Liters.
Define element.
A substance that cannot be decomposed into simpler substances by chemical means.
What is a compound?
A substance composed of 2 or more different elements chemically combined.
What is a mixture?
Two or more substances physically combined.
Differentiate between homogeneous and heterogeneous mixtures.
- Homogeneous mixture = solution = same throughout.
- Heterogeneous mixture = not the same throughout.
What are the three phases of matter?
- Solid (s)
- Liquid (l)
- Gas (g)
What is potential energy?
Stored energy, such as chemical energy in bonds.
What does the term ‘endothermic’ refer to?
Energy is being absorbed.
What is the formula for specific heat capacity?
Q = mCΔT.
What does the first law of thermodynamics state?
Matter and energy are neither created nor destroyed, only transferred.
What is Boyle’s law?
As the pressure on a confined gas increases, the volume decreases (P ↑ V ↓).
What is Charles’ law?
The volume of a gas at constant pressure is directly proportional to its Kelvin temperature (T ↑ V ↑).
What is the Ideal Gas Law?
PV = nRT.
Define ion.
An atom or group of atoms that have a positive or negative charge.
What is an isotope?
An atom with the same number of protons but a different number of neutrons.
What are valence electrons?
Electrons in the outermost principal energy level.
What is the ground state of an electron?
The lowest possible energy state of an electron.
What is the definition of ionization energy?
The energy required to remove an electron from a gaseous atom.
What is Dalton’s Atomic Theory?
Atoms cannot be broken down into smaller particles; atoms of the same element are identical.
What are the groups in the periodic table for Alkali Metals and Noble Gases?
- Group 1 - Alkali Metals
- Group 18 - Noble Gases
What are diatomic molecules?
Molecules consisting of two atoms, e.g., H2, O2, N2.
What are the characteristics of Group 7-11 elements?
Transition Metals have multiple oxidation numbers and colored solutions
What is the main characteristic of Group 17 elements?
Halides/Halogens are nonmetals, highly reactive, and not found in nature alone
What is the main characteristic of Group 18 elements?
Noble Gases are mostly unreactive
Which elements are diatomic?
H2, O2, F2, Br2, I2, N2, Cl2
Which elements are liquids at room temperature?
Hg and Br
What is ionization energy?
The energy required to remove an electron from a gaseous atom
What happens to ionization energy across a period?
It increases
What happens to ionization energy down a group?
It decreases
What is atomic radius?
Half the distance between the nuclei in a molecule consisting of identical atoms
What happens to atomic radius across a period?
It decreases
What happens to atomic radius down a group?
It increases
What is electronegativity?
The tendency of an atom in a molecule to attract shared electrons
What happens to electronegativity across a period?
It increases
What happens to electronegativity down a group?
It decreases
How do metals and non-metals behave in terms of reactivity?
Metals lose electrons, Non-metals gain electrons
Which is the most active metal?
Cesium (Cs)
Which is the most active non-metal?
Fluorine (F)
What does oxidation number represent?
The apparent charge assigned to an atom in a molecule or ion
What is the oxidation number for Group 1 elements?
+1
What is the oxidation number for Group 2 elements?
+2
What is the oxidation number for aluminum?
+3
What is the charge on hydrogen in hydrides?
-1
What is the usual oxidation state of fluorine?
-1
What is the usual oxidation state of oxygen?
-2
What are peroxides?
Compounds where the oxidation state of oxygen is -1
How do you name compounds with multiple oxidation states?
Check for multiple oxidation numbers and solve for the unknown
What is the first step in calculating empirical formulas from percent composition?
Assume 100g | % = grams
What is the equation for percent composition by mass?
% comp by mass = (mass of part / mass of whole) x 100
What is a synthesis reaction?
A reaction where 2 or more reactants combine to form one product
What is a decomposition reaction?
A reaction where a compound breaks down into simpler substances
What is a single replacement reaction?
A reaction where one element replaces another in a compound
What is a double replacement reaction?
A reaction where compounds exchange ions
What is a combustion reaction?
A reaction where a hydrocarbon reacts with oxygen to produce carbon dioxide and water
What is the difference between full molecular, full ionic, and net ionic equations?
Full Molecular: no charges, Full Ionic: only aq substances with charges, Net Ionic: ions involved in the reaction
What is ionic bonding?
Involves the transfer of electrons between metals and nonmetals
What is covalent bonding?
The sharing of electrons between two nonmetals
What is a polar covalent bond?
Unequal sharing of electrons between atoms
What is the bond angle in a linear shape?
180°
What is the bond angle in a bent (angular) shape?
104.5°
What is the bond angle in a trigonal pyramid shape?
107°
What is the bond angle in a tetrahedral shape?
109.5°
