CHEM2 Flashcards
What is the atomic number of an element representative of?
Number of protons
The atomic number is the number of protons in the nucleus of an atom.
An atom that gains electrons will have a _______.
Negative charge
Gaining electrons introduces additional negative charge, leading to a negative ion or anion.
The ‘O’ in H2O is an example of:
Atomic symbol
What is the maximum number of electrons the second shell (shell two) can hold?
8
The second shell can hold a maximum of 8 electrons.
Which type of bond is formed when one atom donates an electron to another?
Ionic bond
Ionic bonds are formed when one atom donates an electron to another, creating cations and anions that attract each other.
The f orbital can hold a maximum of how many electrons?
14
The f orbital has seven subshells and can hold a maximum of 14 electrons (2 electrons per subshell).
How many valence electrons does carbon, with atomic number 6, have in its outer shell?
4
Carbon has 4 valence electrons in its outer shell.
The electron configuration of a neutral atom of chlorine (atomic number 17) ends in:
3p^5
Chlorine has 17 electrons. The electron configuration is 1s^2 2s^2 2p^6 3s^2 3p^5.
Which of the following types of bonds will form between two atoms that share electrons equally?
Nonpolar covalent bond
Nonpolar covalent bonds form when two atoms share electrons equally.
How many d orbitals are there in a d subshell?
5
The d subshell has five d orbitals.
Which shell can hold a maximum of 2 electrons?
First shell
The first shell (often referred to as the K shell) can hold a maximum of 2 electrons.
Which element has the electron configuration 1s^2 2s^2 2p^6?
Neon
The electron configuration provided corresponds to Neon.
Which of the following atoms has the highest electronegativity?
Chlorine
Among the options provided, chlorine has the highest electronegativity.
What type of bond is formed when there is a slight difference in electronegativity, resulting in a slight charge difference but not enough to form an ionic bond?
Polar covalent bond
When there’s a slight difference in electronegativity between two atoms, they form a polar covalent bond.
The third electron shell of an atom can hold a maximum of how many electrons?
18
The third electron shell can hold a maximum of 18 electrons.
Which of the following elements would most likely form an anion by gaining electrons?
Chlorine
Chlorine tends to gain electrons to achieve a full valence shell, becoming an anion in the process.
Which of the following elements is likely to lose an electron to become a cation?
Sodium
Sodium tends to lose one electron to achieve a stable electron configuration, becoming a cation in the process.
What is the primary factor that holds the nucleus of an atom together, despite the repulsive forces between protons?
Strong nuclear force
The strong nuclear force is the force that holds the protons and neutrons together in the nucleus, overcoming the repulsion between protons.
Which of the following elements is most likely to share its electrons when forming a bond?
Chlorine
Chlorine typically forms covalent bonds by sharing its electrons.
Which of the following is NOT a characteristic of covalent bonds?
Occur between metals and nonmetals
Covalent bonds typically occur between nonmetals, whereas ionic bonds usually form between metals and nonmetals.
An atom with 3 protons, 4 neutrons, and 3 electrons would have an atomic number of:
3
The atomic number of an atom is defined by the number of protons it contains.
Which of the following elements is most likely to form a negative ion by gaining electrons?
Chlorine
Chlorine, being a halogen, tends to gain an electron to achieve a full valence shell, thus becoming a negatively charged ion or anion.
What element belongs to Group 1 of the periodic table?
Sodium
Group 1 elements are alkali metals, which include lithium, sodium, potassium, rubidium, cesium, and francium.
Which element has the atomic number 2?
Helium
The atomic number represents the number of protons in an atom.
The number of _________ determines the chemical behavior of an element.
Electrons in the outermost shell
The chemical properties of an element are primarily determined by the number of valence electrons.
Which element is known as the ‘King of Chemicals’?
Hydrogen
Hydrogen is the most abundant element in the universe and involved in numerous chemical reactions.
Which of the following elements is a liquid at room temperature?
Bromine
Bromine is one of only two elements that are liquid at room temperature, along with mercury.
Which element is essential for the functioning of the thyroid gland?
Iodine
Iodine is essential for the production of thyroid hormones, which regulate metabolism.
Which block of the periodic table contains the lanthanides and actinides?
f block
The lanthanides and actinides are positioned separately at the bottom of the periodic table.
Which group of elements is highly reactive and typically stored in oil?
Alkali metals
Alkali metals are stored in oil to prevent reactions with air or moisture.
Which of the following elements is a non-metal that exists in a gaseous state at room temperature?
Nitrogen
Nitrogen exists as a gas (N₂) at room temperature.
Which group of the periodic table contains elements known for their characteristic bright colors and multiple oxidation states?
Transition metals
Transition metals exhibit multiple oxidation states and form colorful compounds.
Which of the following is a metalloid?
Boron
Boron has properties of both metals and non-metals.
Elements in which group are known to form diatomic molecules in their natural form?
Halogens
Halogens naturally exist as diatomic molecules (e.g., F₂, Cl₂).
What is the first element in the periodic table?
Hydrogen
Hydrogen has an atomic number of 1.
Which element is the most electronegative?
Fluorine
Fluorine strongly attracts electrons.
In the periodic table, moving from left to right across a period, the atomic radius generally:
Decreases
The increase in protons pulls electrons closer, decreasing atomic radius.
In which state of matter do particles have the least amount of energy and are closely packed?
Solid
In a solid, particles are tightly packed together and have the least amount of energy compared to liquids and gases.
Which state of matter consists of ionized gas?
Plasma
Plasma is a high-energy state of matter consisting of ionized particles, found in stars and neon lights.
In which state of matter do particles vibrate in fixed positions?
Solid
In a solid, particles are held in a fixed structure and can only vibrate, rather than move freely.
When you increase the pressure on a given amount of gas while keeping the temperature constant, what generally happens to its volume?
Decreases
According to Boyle’s Law, increasing pressure on a gas decreases its volume if the temperature remains constant.
Which of the following is NOT a physical property of matter?
Flammability
Flammability is a chemical property because it describes how a substance reacts with oxygen to produce fire, rather than a physical characteristic like mass or density.
In which state of matter do particles have the highest energy and are spaced farthest apart?
Plasma
Plasma has the highest energy level, as it consists of ionized particles with extremely high kinetic energy, such as in lightning and the Sun.
If the volume of a substance increases while its mass remains the same, its density will:
Decrease
Density is mass divided by volume. If volume increases while mass stays the same, the overall density decreases.
The state of matter in which particles are the least densely packed is:
Gas
In gases, particles are widely spaced and move freely, making them the least dense compared to solids and liquids.
Which of the following best describes the behavior of particles in a solid?
They are packed closely and vibrate in place.
In solids, particles remain in fixed positions and only vibrate rather than moving freely like liquids or gases.
If you decrease the volume of a gas while keeping its temperature constant, what will happen to its pressure?
It will increase.
According to Boyle’s Law, reducing the volume of a gas increases its pressure when temperature remains constant.
When a substance changes from a liquid to a solid, it typically:
Decreases in volume
Most substances contract when freezing, meaning their volume decreases as the particles pack closer together.
An increase in which of the following will cause a gas to condense into a liquid?
Pressure
Increasing pressure forces gas particles closer together, leading to condensation and turning the gas into a liquid.
In which state of matter are particles ionized and have the highest energy?
Plasma
Plasma consists of ionized particles with very high energy, found in the Sun, lightning, and neon lights.
When you heat a solid, its particles:
Vibrate more vigorously
Heating increases the energy of solid particles, making them vibrate more, which can eventually lead to melting.
What is the primary factor determining the state of matter of a substance at room temperature?
Temperature
Temperature is the key factor that determines whether a substance exists as a solid, liquid, or gas at room temperature.
Which state of matter does not have a definite shape but has a definite volume?
Liquid
Liquids take the shape of their container but maintain a fixed volume, unlike gases that expand to fill the container.
Which of the following phase changes requires the absorption of heat energy?
Vaporization
Vaporization (liquid to gas) requires heat energy to break intermolecular forces and allow particles to move freely.
When a liquid turns into a gas below its boiling point, the process is called:
Evaporation
Evaporation occurs when molecules at the surface of a liquid gain enough energy to turn into gas without reaching boiling temperature.
In which state of matter are particles packed the closest together?
Solid
In a solid, particles are arranged in a tightly packed structure, making it the most dense state of matter.
What type of reaction occurs when zinc reacts with hydrochloric acid?
Displacement
In a displacement reaction, one element replaces another in a compound.
What is the term for the number placed before the formula of a reactant or product in a chemical equation?
Coefficient
The coefficient indicates the number of molecules or moles of a substance in a reaction.
In the reaction CH₄ + 2O₂ → CO₂ + 2H₂O, how many moles of oxygen react with one mole of methane?
2
One mole of CH₄ reacts with two moles of O₂ to produce CO₂ and H₂O.
If 4 moles of hydrogen gas react with 2 moles of oxygen gas to produce water, how many moles of water will be formed?
4
The balanced reaction is: 2H₂ + O₂ → 2H₂O, meaning 4 moles of H₂ produce 4 moles of H₂O.
What do you call a small whole number that appears as a factor in front of a formula in a chemical equation?
Coefficient
A coefficient represents the number of molecules or moles of a substance in a balanced chemical equation.
What is the statement that the total mass of reactants in a chemical reaction is always equal to the total mass of the products?
Law of conservation of mass
This law states that mass cannot be created or destroyed in a chemical reaction.
What do you call the amount of substance that contains as many entities as there are atoms in 12 g of carbon-12?
Mole
A mole represents 6.022 × 10²³ particles (atoms, molecules, or ions) of a substance.
If a balanced chemical equation has coefficients 2, 1, and 2 for the reactants and products, how many moles of the first reactant will be required to produce 4 moles of the second product?
2
To produce 4 moles of the product, 2 moles of the first reactant are needed.
Which of the following is NOT a product of the combustion of propane (C₃H₈)?
O₂
The combustion of propane produces CO₂, H₂O, and heat; O₂ is a reactant.
If you know the quantities of reactants used and the quantities of products formed in a chemical reaction, you are dealing with:
Stoichiometric calculations
Stoichiometry involves calculating the amounts of reactants and products based on the balanced equation.
When zinc metal is added to hydrochloric acid, what type of reaction occurs?
Single displacement
Zinc displaces hydrogen from hydrochloric acid, forming zinc chloride and releasing hydrogen gas.
In the balanced chemical equation N₂ + 3H₂ → 2NH₃, what does the ‘3’ in front of H₂ represent?
Coefficient
A coefficient represents the number of molecules or moles of a substance involved in the reaction.
A chemical reaction that requires an input of energy to proceed is said to be:
Endergonic
Endergonic reactions absorb energy from their surroundings in order to proceed.
What type of chemical reaction occurs when an acid and a base combine to produce water and a salt?
Neutralization
A neutralization reaction occurs when an acid reacts with a base to produce a salt and water.
Which among the following is NOT a sign of a chemical reaction?
Boiling of liquid
Boiling is a physical change and does not change the chemical composition of the substance.
What type of reaction involves an element reacting with a compound and displacing another element from it?
Single displacement
In a single displacement reaction, one element replaces another element in a compound.
The small whole number that appears in front of a formula in a balanced chemical equation represents:
Coefficient
The coefficient represents the number of molecules or moles of a substance involved in a reaction.
A chemical reaction in which both oxidation and reduction processes occur is termed:
Redox reaction
In redox reactions, one substance loses electrons (oxidation) while another gains electrons (reduction).
Which of the following is an example of a combustion reaction?
Burning a candle
Combustion reactions involve burning a substance in the presence of oxygen to produce heat, light, CO₂, and H₂O.
In a balanced chemical equation, if you change the coefficient of a reactant or product, you must adjust:
Other coefficients in the equation to maintain balance
Changing one coefficient affects the balance of atoms, so other coefficients must also be adjusted.
In a combustion reaction involving hydrogen gas, which of the following products is formed?
Water (H₂O)
The combustion of hydrogen gas (H₂) in oxygen (O₂) produces water (H₂O) as the product.
In an exothermic reaction, what happens to the energy of the system?
Released to surroundings
Exothermic reactions release energy, usually in the form of heat, as the reaction proceeds.
If pressure is increased on a gaseous system, in which direction will the equilibrium shift for a reaction with fewer moles of gas on the product side?
Left, towards reactants
According to Le Chatelier’s principle, an increase in pressure favors the side with fewer gas molecules to reduce pressure.
Which of the following is NOT true about static equilibrium?
Concentrations of products are always higher
In static equilibrium, the concentration of reactants and products remains constant, but one is not necessarily higher than the other.
For the reaction: N₂(g) + 3H₂(g) ⇌ 2NH₃(g), what will happen if the concentration of N₂ is decreased?
Shift to the left
A decrease in the concentration of a reactant shifts the equilibrium towards the reactants to compensate.
What is the role of a catalyst in a chemical reaction?
Provide alternate pathway with lower activation energy
Catalysts speed up reactions by lowering the activation energy required, without being consumed in the process.
How does a catalyst affect the activation energy of a reaction?
Decreases it
Catalysts reduce the activation energy, allowing the reaction to proceed faster.
For a gaseous reaction at equilibrium, increasing the volume of the container will:
Favor the side with more moles of gas
Increasing volume decreases pressure, which shifts the equilibrium towards the side with more gas molecules.
How does a decrease in temperature affect an exothermic reaction at equilibrium?
Shifts towards products
Lowering the temperature favors the exothermic direction, as the system tries to replace the lost heat.
Which of the following is true about catalysts?
They provide an alternate pathway for the reaction
Catalysts speed up reactions by offering a lower-energy pathway for the reactants to convert into products.
For a given reaction, if the concentration of reactants is doubled, the reaction will:
Shift to the right
Increasing reactant concentration pushes the equilibrium towards the products.
An increase in pressure in a system at equilibrium will favor the side with:
Fewer moles of gas
Increased pressure favors the side with fewer gas molecules to reduce pressure.
In an endothermic reaction:
Heat is treated as a reactant
Endothermic reactions absorb heat, so heat is considered a reactant.
What effect does decreasing temperature have on an endothermic reaction at equilibrium?
Shifts left
Lowering temperature in an endothermic reaction shifts the equilibrium toward the reactants.
When a system in equilibrium is compressed, the reaction will favor the side with:
The least moles of gas
Compression increases pressure, favoring the side with fewer gas molecules.
Which of these reactions would be least affected by a change in pressure?
A(g) + B(g) ⇌ C(l) + D(s)
Reactions that involve solids and liquids are the least affected by pressure changes.
What happens to the position of equilibrium when a reactant is added?
Shifts to the right
Adding more reactant pushes the equilibrium towards the products.
In which of these scenarios would Le Chatelier’s principle predict no change in the position of equilibrium?
Addition of a catalyst
Catalysts speed up the reaction but do not change the position of equilibrium.
If the concentration of a product is decreased in a reaction at equilibrium, the equilibrium will:
Shift to the right
Removing product shifts the reaction toward producing more of it.
Which of the following best describes a dynamic equilibrium?
Both forward and reverse reactions are occurring at the same rate
At dynamic equilibrium, the rate of the forward reaction equals the rate of the reverse reaction.
According to Le Chatelier’s principle, if a system at equilibrium is subjected to a decrease in temperature, how will it respond?
By shifting to counteract the change
The system will shift to produce more heat if the temperature is decreased.
Which of the following changes would NOT cause a shift in the position of equilibrium?
Adding a catalyst
Catalysts only speed up equilibrium attainment but do not affect its position.
In a chemical reaction, if the system is at equilibrium and the concentration of a reactant is increased, the reaction will:
Shift to the right
Increasing reactant concentration pushes equilibrium toward the products.
Which statement is true regarding an endothermic reaction?
The reaction absorbs heat
Endothermic reactions take in heat from the surroundings.
Which of the following best describes how a catalyst works?
It provides an alternate pathway for the reaction with a lower activation energy
A catalyst lowers activation energy, making the reaction proceed faster.
If the concentration of products is decreased in a reaction at equilibrium, the system will:
Shift to the right
Removing products shifts the equilibrium towards producing more products.
According to Le Chatelier’s principle, if a system at equilibrium is disturbed, the system will:
Shift to counteract the disturbance
The system adjusts itself to oppose any changes imposed on it.
In an exothermic reaction, heat is:
Released into the surroundings
Exothermic reactions release heat as a product.
In a system at equilibrium, if the temperature is increased, the reaction will:
Favor the endothermic reaction
Increasing temperature favors the reaction that absorbs heat (endothermic).
Which of the following changes would result in an increase in the rate of attainment of equilibrium?
Adding a catalyst
Catalysts increase the reaction rate, helping equilibrium to be reached faster.
In a system at equilibrium, if the pressure is increased, the equilibrium will:
Shift to the side with fewer moles of gas
Increased pressure shifts equilibrium toward the side with fewer gas molecules.
According to Le Chatelier’s principle, if a system at equilibrium is subjected to an increase in concentration of reactants, the system will:
Shift to the right
Increasing reactants pushes the reaction toward producing more products.
Adhesion is best represented by which of the following scenarios?
Water droplets forming on a spider web
Adhesion refers to the attraction between molecules of different substances.
How does the polarity of water molecules contribute to its cohesive properties?
The partial positive charge on oxygen in one water molecule attracts the partial negative charge on hydrogen in another molecule
Cohesion refers to the attraction between like molecules due to hydrogen bonding.
What is solubility?
The maximum amount of solute that can dissolve in a specific solvent at a given temperature
Solubility is a quantitative property describing how much of a substance can dissolve in a solvent.
Which of the following is an example of a hydrophilic substance?
Ethanol
Hydrophilic substances dissolve in water due to their ability to form hydrogen bonds.
If you were to add more solute to a saturated solution at room temperature:
The solute would not dissolve and would settle at the bottom
A saturated solution has dissolved the maximum amount of solute at that temperature.
Which of the following is NOT a solution?
A chunk of gold
A solution is a homogeneous mixture, while a pure chunk of gold is not a mixture.
In terms of solubility, how do gases behave with an increase in temperature?
Their solubility decreases
Gases become less soluble in liquids as temperature increases due to increased kinetic energy.
Which of the following statements about diffusion is correct?
It results in an even distribution of particles
Diffusion involves the movement of molecules from high to low concentration.
Which scenario best represents cohesion?
Water droplets sticking to each other on a spider web
Cohesion refers to the attraction between molecules of the same substance.
In osmosis, water moves:
Towards the area of higher solute concentration
Osmosis is the movement of water across a semipermeable membrane to balance concentration differences.
Which of the following describes the main difference between a polar and a non-polar molecule?
Non-polar molecules have an equal distribution of electrical charge
Polar molecules have regions of partial charge due to uneven electron distribution.
Hydrophilic substances:
Are attracted to water and can often dissolve in it
Hydrophilic substances interact with water through hydrogen bonding.
Which of the following scenarios best demonstrates the concept of diffusion?
Perfume spreading throughout a room
Diffusion involves molecules moving from high to low concentration.
Water’s ability to move up a thin tube against the force of gravity is due to:
Both its cohesive and adhesive properties
Adhesion helps water stick to the tube’s walls, while cohesion allows water molecules to pull each other up.
In the sodium-potassium pump:
2 sodium ions are pumped out of the cell and 3 potassium ions are pumped into the cell
The sodium-potassium pump actively transports ions to maintain cellular balance.
Which type of transport is responsible for maintaining the cell’s internal environment by removing or adding specific substances?
Active transport
Active transport moves substances against their concentration gradient.
What role do buffers play in solutions?
Maintain a stable pH
Buffers resist changes in pH when acids or bases are added, helping maintain a stable pH.
Which compound acts as a base in the following reaction? HCl + NaOH -> NaCl + H2O
NaOH
Sodium hydroxide (NaOH) is a base and reacts with the acid HCl in this reaction.
In the reaction of an acid and a base, what is primarily formed?
Salt and water
A neutralization reaction between an acid and a base typically results in the formation of salt and water.
What will neutralize a base?
Acid
Acids neutralize bases in neutralization reactions.
What is a common use for bases?
In the production of soap
Bases, such as sodium hydroxide, are commonly used in soap production.
What substance can act as both an acid and a base?
H2O
Water can donate protons (H+) and accept protons, thus acting as both an acid and a base.
What does a neutralization reaction produce?
Salt and water
A neutralization reaction between an acid and a base results in the formation of salt and water.
Which system helps regulate acid-base balance?
Respiratory system
The respiratory system, along with the renal system, plays a significant role in maintaining acid-base homeostasis in the human body.
A substance that donates protons (H+) in a solution is classified as:
An acid
Acids are substances that donate protons (H+) when they dissolve in water.
The bicarbonate system in the blood is an example of:
Buffer
Buffers help maintain the pH balance in the blood, with the bicarbonate system being a key component.
Which of the following reactions describes the neutralization process?
Acid + Base -> Salt + Water
A neutralization reaction involves the reaction of an acid and a base to produce salt and water.
Which ion is common in all acidic solutions?
H+
The presence of hydrogen ions (H+) is what characterizes acidic solutions.
