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Chemistr Definitions
All the definitions from grade 9 chemistry
Term | Definition |
---|---|
Matter | anything that has mass and takes up space |
pure substance | matter that contains only one kind of particle |
mixture | matter that contains more than one kind of particle |
element | a pure substance that cannot be broken down into simpler parts by chemical methods |
compound | a pure substance made of two or more different elements that are chemically combined |
physical property | a characteristic of a substance that can be observed and measured without changing the identity of the substance |
viscosity | the measure of a substance's ability to flow |
melting point | the temperature at which a solid turns into a liquid |
boiling point | the temperature at which a liquid turns into a gas |
solubility | a measure of the ability of a substance to dissolve in another substance |
density | the ratio of the mass of a substance the volume it occupies |
chemical property | the ability of a substance to change (react) and form a new substance |
combustibility | the ability of a substance to burn in air |
stability | the ability of a substance to remain uncharged |
toxicity | the ability of a substance to cause harmful effects in plants and animals |
atom | the smallest particle of an element that retains the identity of the element. |
electron | a negatively charged particle within the atom |
subatomic particle | a particle that is smaller than the atom |
nucleus | in chemistry, the positively charged centre of an atom. |
proton | a positively charged particle that is part of every atomic nucleus |
neutron | an uncharged particle that is part of almost every atomic nucleus |
atomic number | the number of protons in the nucleus of an atom |
mass number | the sum of the number of protons and the number of neutrons in the nucleus of an atom |
isotope | one of two or more forms of an element that have the same number of protons but a different number of neutrons |
atomic mass | the average mass of the naturally occurring isotopes of an element |
periodic table | a system for organizing the elements into columns and rows, so that elements with similar properties are in the same column |
metal | typically, an element that is hard, shiny, malleable, and ductile, and is a good conductor of heat and electricity. |
non-metal | typically, and element that is not shiny, malleable or ductile and is a poor conductor of heat and electricity |
metalloid | an element that shares some properties with metals and some properties with non-metals |
period | a horizontal row of elements in the periodic table |
group | a vertical column of elements in the periodic table |
valence electron | an electron in the outermost occupied energy level of an atom. |
ion | a positively or negatively charged atom or molecule |
chemical bond | a chemical link between two atoms, which holds the atoms together |
ionic bond | a chemical bond that forms between oppositely charged ions |
ionic compound | a compound made of oppositely charged ions |
molecular compound | a compound formed when atoms of two or more different elements share electrons |
covalent bond | a chemical bond in which one or more pairs of electrons are shared by two atoms |
molecule | the smallest discrete particle of a pure substance, which has one or more shared pairs of electrons |