Regents Chemistry Flash Cards

Definition of Atoms

Atoms are the fundamental building blocks of all elements, composed of electrons, protons, and neutrons.

Electrons

Carry a negative charge, have negligible mass, occupy space around the nucleus, and dictate the volume and size of the atom.

Protons

Carry a positive charge with a mass of exactly 1 amu, located in the nucleus, and determine the identity of the element.

Neutrons

Carry a neutral charge, have a mass of 1 amu, and reside in the nucleus.

The Nucleus

Small, dense, and positively charged center of the atom where most of its mass (protons + neutrons) is concentrated.

Ions

Charged particles formed by a change in the number of electrons.

Cations

Positively charged ions formed by losing electrons.

Anions

Negatively charged ions formed by gaining electrons.

Isotopes

Atoms of the same element with different numbers of neutrons and thus different mass numbers.

Average Atomic Mass

Calculated based on the mass and relative abundance of all naturally occurring isotopes of an element.

Ground State

The relaxed state where all electrons are in their lowest possible energy levels.

Excited State

State when an electron absorbs energy and is promoted to a higher orbital.

Electromagnetic Spectrum

Light travels in waves with peaks and dips; wavelength and frequency are key properties.

Valence Electrons

Electrons in the outermost shell that dictate chemical reactivity.

Periodic Table Organization

Arranged in order of increasing atomic number (number of protons).

Group 1

Alkali Metals: Very reactive with 1 valence electron.

Group 2

Alkaline Earth Metals: Reactive with 2 valence electrons.

Group 17

Halogens: Highly reactive non-metals with high electronegativity.

Group 18

Noble Gases: Unreactive due to a complete octet of 8 valence electrons.

Chemical Bonding

Atoms react to achieve a stable configuration of 8 valence electrons.

Ionic Bonding

Occurs between a metal and a non-metal involving a complete transfer of electrons.

Covalent Bonding

Occurs between two non-metals involving the sharing of electrons.

Bond Polarity

Determined by the difference in electronegativity; can be polar or non-polar.

Intermolecular Forces (IMF)

Forces of attraction between molecules, ranked by strength.

Hydrogen Bonding

Strongest IMF occurring when hydrogen is bonded to F, O, or N.

Boiling Point Connection

Stronger IMFs lead to higher boiling points as more energy is needed to break attractions.

Types of Reactions

Include synthesis, decomposition, single replacement, double replacement, and combustion.

Conservation of Mass

In a chemical reaction, the number of atoms must equal on both sides.

Stoichiometry

Using balanced equation coefficients as molar ratios to predict product yield.

Avogadro's Number

One mole equals 6.02 × 10^23 particles.

Limiting Reagent

The reactant that is completely consumed first limiting the amount of product made.

Percent Composition

Mass of part divided by mass of whole times 100.

Solutes and Solvents

Solute is the substance being dissolved, and solvent is the dissolving agent.

pH Scale

Ranges from 0 to 14; pH < 7 is acidic, = 7 is neutral, and > 7 is basic.

OIL RIG Mnemonic

Oxidation Is Losing, Reduction Is Gaining.

Radioactivity

Spontaneous breakdown of unstable nuclei.

Half-Life

Time required for half of a radioactive sample to decay.

Fission

A heavy nucleus splits into smaller nuclei.

Fusion

Small nuclei combine to form a heavier nucleus.

Gold Foil Experiment

Conducted by Ernest Rutherford, this experiment demonstrated that atoms have a dense nucleus as positively charged particles were deflected when aimed at a thin gold foil, indicating most of the atom is empty space.

Bohr Model of the Atom

A model proposed by Niels Bohr, depicting electrons orbiting the nucleus in fixed paths or energy levels, illustrating quantization of electron energy.

Valence Shell Electron Pair Repulsion (VSEPR) Theory

A theory that predicts the geometry of individual molecules based on the repulsion between electron pairs in the valence shell.

Periodic Trends

Trends observed in the periodic table, including atomic radius, ionization energy, electronegativity, and electron affinity, which relate to the structure of the atoms.

Electronegativity

A measure of the ability of an atom to attract electrons in a chemical bond, often represented by the Pauling scale.

Acids and Bases

Acids are substances that donate protons (H⁺ ions), while bases are substances that accept protons; they play a critical role in chemical reactions.

Le Chatelier's Principle

A principle stating that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change and restore a new equilibrium.

Dalton's Atomic Theory

A theory proposed by John Dalton that states matter is made up of indivisible atoms, which combine in whole number ratios to form compounds.

Synthesis Reaction

A type of chemical reaction where two or more simple substances combine to form a more complex product.

Decomposition Reaction

A reaction in which a single compound breaks down into two or more simpler products.

Redox Reaction

A type of chemical reaction that involves the transfer of electrons between substances, combining reduction and oxidation processes.

Kinetic Molecular Theory

A theory that explains the behavior of gases, stating that particles are in constant motion and the pressure exerted by a gas is a result of collisions between the particles and the walls of the container.