31 terms

Chapter 2 The chemical level

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chemistry
the science of the structure and interactions of matter
chemical element
a substance that cannot be split into a simpler substance by ordinary chemical means
atom
the smallest unit of matter that retains the properties and characteristics of the element
atomic number
the number of protons in the nucleus of an atom
proton
positively charged subatomic particle within the atomic nucleus
neutron
uncharged (neutral) subatomic particle within the atomic nucleus
electron
negatively charged subatomic particle that moves about in a large space surrounding the nucleus
isotope
atom of an element containing a different number of neutrons
compared to another atom of the same element
mass number
the total number of subatomic particles in the nucleus of an atom (protons + neutrons)
radioactive isotope
unstable isotope that can undergo spontaneous decay into a more stable form
During decay they emit radiation of either subatomic particles or packets of energy
In the process of decay it often transforms into a different element
half life
the time required for half of the radioactive atoms in a sample of a specific isotope
to decay into a more stable form
atomic mass unit (dalton)
the standard unit for measuring the mass of atoms and subatomic particles
A neutron and a proton each have a mass of approximately 1 dalton
ion
an atom that has a positive or negative charge because it has unequal numbers of protons and electrons
formed when a neutral atom gains or loses one or more electrons
molecule
a combination of atoms that are connected because they share electrons with each other
molecular formula
a way of indicating which elements and how many atoms of each element
are present in a specific molecule
compound
a substance that contains atoms of two or more different elements
valence shell
the outermost shell of an atom
octet rule
eight electrons in a valence shell is a more stable arrangement than some other number
chemical bond
the force that holds together the atoms of a molecule or compound
covalent bond
a force that holds together atoms through those atoms sharing electrons
single covalent bond
the chemical bond formed when two atoms share one electron pair (2 electrons)
double covalent bond
the chemical bond formed when two atoms share two pairs of electrons (4 electrons)
triple covalent bond
the chemical bond formed when two atoms share three pairs of electrons (6 electrons)
Electronegativity
the power that an atom has to attract electrons to itself
nonpolar covalent bond
a covalent bond in which atoms share the electrons equally
polar covalent bond
a covalent bond in which atoms share the electrons unequally
ionic bond
a force that holds together positive and negative ions
cation
a positively charged ion (an atom that has less electrons than protons)
anion
a negatively charged ion (an atom that has more electrons than protons)
electrolyte
an ionic compound that breaks apart into positive and negative ions in solution
hydrogen bond
a chemical bond that forms when a hydrogen atom with a partial positive charge attracts the partial negative charge of neighboring electronegative atom, most often oxygen or nitrogen.
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