NYS Regents Chemistry Flashcards

Atomic Composition

• Neutrons carry no charge and have a mass of 1 atomic mass unit; they are located in the nucleus.
• Protons possess a positive charge and are also found in the nucleus.
• Electrons are negatively charged and reside outside the nucleus.
• The atomic number indicates the number of protons (and electrons) in an atom.

Atomic Structure

• An atom consists of a nucleus at its core, containing protons and neutrons, with electrons orbiting outside.
• The mass number is the total count of protons and neutrons in an atom.

Isotopes and Nuclide Symbols

• Isotopes share the same atomic number but vary in mass number due to differing neutron counts.
• Nuclide symbols serve as shorthand to denote an element's atomic number and mass number.

Nuclear Characteristics

• Nuclear charge, determined by the atomic number, reflects the total positive charge of the nucleus.
• The stability of isotopes is influenced by the neutron-to-proton ratio.

Electron Configurations and Energy Levels

• Energy levels can accommodate a maximum number of electrons, with the first level housing those with the lowest energy.
• Electrons in outermost levels carry the highest energy.
• Valence electrons are those located in the outermost energy level and dictate chemical behavior.

Atomic Mass and Properties

• Average atomic mass is calculated by taking the sum of the percent abundance of each isotope divided by 100, then multiplied by the mass of the isotope.
• Conducting a flame test can excite an electron, causing it to jump to a higher energy state, which produces a bright line spectrum when viewed through a prism.

Historical Experiments and Models

• Rutherford's Gold Foil Experiment revealed that atoms consist of a dense, positively charged nucleus surrounded by mostly empty space.
• The Wave Model of the Atom introduces the concept of orbitals as regions where electrons are likely to be found.

Periodic Table and Atomic Properties

• The modern periodic table organizes elements by increasing atomic number.
• First ionization energy is the energy required to remove an electron from an atom, while electronegativity describes an atom's ability to attract electrons.
• Melting point and boiling point refer to the temperatures where solids become liquids and liquids become gases, respectively.

Density and Atomic Radius

• Density is defined as mass per unit volume, while atomic radius indicates the size of an atom.

Classification of Elements

• Metals typically appear on the left side of the periodic table, characterized by low electronegativity, low ionization energy, malleability, ductility, and excellent conductivity.
• Nonmetals are predominantly found on the right side, exhibiting high electronegativity, high ionization energy, brittleness in solid form, and poor conductivity.
• Metalloids possess properties that are intermediate between metals and nonmetals.