Science (Ch 2) Flashcards
Matter
anything that has mass and takes up space.
Atom
the smallest particle of an element that still retains the properties of the element.
Element
substance that is made of only one type of atom.
Proton
particle inside the nucleus of an atom that has a charge of 1+.
Neutron
particle without an electrical charge.
Electron
particle with a negative charge.
Atomic Number
number of protons in an atom’s nucleus.
Mass number
the number of protons plus the number of neutrons in an atom.
Isotope
atoms of the same element that have different numbers of neutrons.
Compound
atoms of more than one type of element that are chemically bonded together.
Molecule
a group of atoms connected by covalent bonds.
Ion
electrically-charged atom whose charge results from an atom losing or gaining electrons.
Mixture
a combination of substances in which the individual substances do not change or combine chemically but instead retain their own individual properties; can be gases, solids, liquids, or any combination of them.
Heterogeneous mixture
a mixture which is not mixed evenly and each component retains its own properties.
Homogeneous mixture
solid, liquid, or gas that contains two or more substances blended evenly throughout.
Solution
a mixture which is evenly mixed throughout; also known as a homogeneous mixture.
Density
measurement of the mass of an object divided by its volume.
John Dalton theory of atoms:
- Every element is made of tiny, unique particles called atoms that CANNOT be subdivided.
- Atoms of the same element are exactly alike.
- Atoms of different elements can join to form molecules.
Niels Bohr suggested that electrons:
electrons move in set paths like planets that surround the sun.
There are energy levels in which ___________ must move through. When an electron gains energy, it moves to a _________ _________ level. When it loses energy, it moves to a ________ __________ level.
There are energy levels in which electrons** must move through. When an electron gains energy, it moves to a **higher energy** level. When it loses energy, it moves to a **lower energy level.
There are energy levels in which e_______ must move through. When an electron gains energy, it m_____ to a h______ e______ l_____. When it loses energy, it moves to a l_______ e_______ l______.
There are energy levels in which electrons must move through. When an electron gains energy, it moves to a higher energy level**. When it loses energy, it moves to a **lower energy level.
There are energy levels in which _________ must move through. When an electron gains energy, it _____ to ______ ______ _____. When it loses energy, it moves to a _______ _______ ______.
There are energy levels in which electrons must move through. When an electron gains energy, it moves to a higher energy level**. When it loses energy, it moves to a **lower energy level.
In the modern atomic model, electrons are found
in orbitals (s, p, d, f…) within each energy level.
The electrons in the outermost energy level are called:
_ valence electrons._
