Basic Chemistry Flashcards
What’s the difference between an element and a compound?
An element is a single type of atom; a compound is two or more elements bonded together.
What’s the most common element in the atmosphere?
Nitrogen (78%).
What element is essential for combustion?
Oxygen.
What’s the chemical formula for water?
H₂O.
What does ‘diatomic’ mean in chemistry?
A molecule made of two atoms, like O₂ or H₂.
What element is found in all organic compounds?
Carbon.
What’s the chemical symbol for chlorine?
Cl.
What’s the formula for carbon monoxide?
CO.
What’s the primary health difference between CO and CO₂?
CO is toxic, CO₂ is an asphyxiant.
What’s the formula for ammonia?
NH₃.
What are the three main states of matter?
Solid, liquid, gas.
What’s a fourth state of matter found in fires?
Plasma.
What phase change occurs when a solid turns into a gas?
Sublimation.
What’s the process of a gas turning into a liquid?
Condensation.
What’s the boiling point of water?
212°F (100°C).
What’s the freezing point of water?
32°F (0°C).
What’s the main difference between evaporation and boiling?
Evaporation happens at any temperature; boiling requires heat above the boiling point.
What is the term for a liquid changing to gas at temperatures below its boiling point?
Evaporation.
What phase change happens in a BLEVE?
Rapid liquid-to-gas expansion.
What’s an example of sublimation in hazmat?
Dry ice (CO₂) turning into gas.
What are the two main types of chemical bonds?
Ionic and covalent.
What happens in an exothermic reaction?
It releases heat.
What’s an example of an exothermic reaction in hazmat?
Combustion.
What happens in an endothermic reaction?
It absorbs heat.
What’s an example of an endothermic reaction?
Ammonium nitrate dissolving in water.
What happens when an acid and base mix?
Neutralization, producing salt and water.
What’s an example of a violent acid-base reaction?
Sulfuric acid and sodium hydroxide.
What gas is released when metals react with acids?
Hydrogen gas.
What’s the danger of organic peroxides?
Highly unstable, can self-react explosively.
What’s the hazard of alkali metals in water?
Violent reaction with fire or explosion.
What does pH measure?
Acidity or alkalinity of a substance.
What pH range is acidic?
0-6.
What pH range is basic (alkaline)?
8-14.
What pH is neutral?
7.
What’s an example of a strong acid?
Hydrochloric acid (HCl).
What’s an example of a strong base?
Sodium hydroxide (NaOH).
What’s the hazard of mixing acids and bases?
Violent reaction with heat and gas release.
What’s the main hazard of hydrofluoric acid?
Absorbs into skin and attacks bones.
What PPE is required for handling strong acids or bases?
Chemical-resistant gloves and suit
Level A
What does a pH of 1 indicate?
Extremely acidic, highly corrosive.
What is the flashpoint of a liquid?
Lowest temperature where vapors can ignite.
What’s an example of a flammable liquid?
Gasoline.
What’s an example of a combustible liquid?
Diesel fuel.
What’s the lower explosive limit (LEL)?
Minimum vapor concentration needed to ignite.
What’s the upper explosive limit (UEL)?
Maximum vapor concentration that can ignite.
What’s the hazard of exceeding the UEL?
Too rich to burn but can ignite if diluted or ignite towards end of range
May be large quantities displacing 02
What’s the hazard of a hydrocarbon spill on water?
Vapors travel along the surface and can ignite.
What does vapor density <1 mean?
It rises in air (lighter than air).
What does vapor density >1 mean?
It sinks in air (heavier than air).
What’s a common heavy vapor hazard?
Propane accumulating in low areas.
What does an oxidizer do?
Supports combustion, doesn’t burn itself.
What’s an example of an oxidizer?
Ammonium nitrate.
What’s the hazard of mixing oxidizers with fuels?
Increased fire or explosion risk.
What’s the hazard of chlorine reacting with organics?
Can create toxic and flammable gases.
What’s the primary hazard of peroxides?
Unstable, can self-react explosively.
What’s the risk of nitric acid with metals?
Produces toxic nitrogen dioxide gas.
What’s a common shock-sensitive explosive?
Picric acid if dried out.
What’s a water-reactive metal?
Sodium or potassium.
What’s a key sign of an unstable reactive material?
Crystals forming around the cap.
What’s the hazard of aluminum powder near an oxidizer?
Can cause a thermite-like reaction.
What is the smallest unit of an element?
Atom
True or False: A molecule is made up of two or more atoms bonded together.
True
Fill in the blank: The chemical bond formed by the sharing of electrons is called a __________ bond.
Covalent
What type of bond involves the transfer of electrons from one atom to another?
Ionic bond
Which subatomic particle has a positive charge?
Proton
What is the charge of a neutron?
Neutral
What is the term for the number of protons in the nucleus of an atom?
Atomic number
True or False: Electrons are found in the nucleus of an atom.
False
Fill in the blank: The outermost shell of an atom is known as the __________ shell.
Valence
What is the main difference between an element and a compound?
An element is a pure substance made of one type of atom, while a compound is made of two or more different types of atoms bonded together.
What kind of bond is formed between two metal atoms?
Metallic bond
Multiple Choice: Which particle determines the chemical properties of an atom? A) Neutrons B) Protons C) Electrons D) Nucleus
C) Electrons
True or False: Isotopes of an element have the same number of protons but different numbers of neutrons.
True
What is the formula for calculating the maximum number of electrons in a shell?
2n^2, where n is the shell level.
Fill in the blank: The chemical formula for water is __________.
H2O
What is the primary force that holds atoms together in a molecule?
Chemical bonds
Multiple Choice: Which of the following represents a polar covalent bond? A) H2 B) HCl C) NaCl D) O2
B) HCl
What is the pH range of acidic solutions?
0 to 7
True or False: The atomic mass of an element is the weighted average of the masses of its isotopes.
True
Fill in the blank: The substance formed when two or more elements are chemically bonded is called a __________.
Compound
What is a characteristic property of ionic compounds?
They typically form crystalline structures and have high melting and boiling points.
What is the role of valence electrons in chemical bonding?
Valence electrons are involved in the formation of bonds between atoms.
Multiple Choice: Which element is most likely to form a cation? A) Sodium B) Chlorine C) Oxygen D) Neon
A) Sodium
True or False: A double bond involves the sharing of four electrons between two atoms.
True
What is the difference between a molecule and a compound?
A molecule can consist of two or more atoms of the same or different elements, whereas a compound specifically consists of two or more different elements.
