science 10 reveiw Flashcards
what is a proton
A subatomic particle found in the nucleus of an atom, with a positive electric charge. The number of protons determines the element’s atomic number.
neutron
A subatomic particle found in the nucleus of an atom, with no charge (neutral). Neutrons contribute to the atomic mass but don’t affect the chemical properties of an element.
electron
A subatomic particle with a negative electric charge, found in the electron cloud surrounding the nucleus. Electrons are involved in chemical bonding and reactions.
atom
The basic unit of matter, consisting of a nucleus (made up of protons and neutrons) and an electron cloud. Atoms combine to form molecules.
ion
An atom or molecule that has gained or lost one or more electrons, resulting in a charged particle. Ions can be positive (cation) or negative (anion).
valence electron
The electrons in the outermost electron shell of an atom. These electrons are involved in forming chemical bonds and determining an element’s reactivity.
octet rule
A chemical rule of thumb that atoms tend to form bonds in such a way that each atom achieves a full outer shell of eight electrons, similar to the electron configuration of noble gases.
monovalent
Refers to an atom or ion that can form only one bond or has a valence of one. For example, hydrogen (H) and sodium (Na) are monovalent.
multivalent
Refers to an atom or ion that can form multiple bonds or can have more than one possible valence (oxidation state). For example, iron (Fe) can be Fe²⁺ or Fe³⁺.
endothermic
A process or reaction that absorbs energy (usually in the form of heat) from its surroundings. An example is the process of photosynthesis.
exothermic
A process or reaction that releases energy (usually in the form of heat) to its surroundings. Combustion reactions are typical examples.
law of conservation of matter
A fundamental principle stating that matter cannot be created or destroyed in a chemical reaction. The total mass of the reactants is equal to the total mass of the products.
molar mass
The mass of one mole of a substance, usually expressed in grams per mole (g/mol). It is numerically equivalent to the substance’s atomic or molecular weight.
Mole
A unit of measurement for the amount of substance. One mole represents
6.022
×
10
23
6.022×10
23
particles (atoms, molecules, etc.), known as Avogadro’s number.
mass number
The total number of protons and neutrons in the nucleus of an atom. This number is used to distinguish between isotopes of an element.
isotope
Atoms of the same element that have the same number of protons but different numbers of neutrons. Isotopes have the same chemical properties but may differ in physical properties (e.g., carbon-12 vs. carbon-14).
