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Biology 125/ Chapter 2.1/ Powless (The Nature of Matter)

Terms in this set (15)

The basic unit of matter is called a(an)
atom
Describe the nucleus of an atom.
a nucleus is at the center of the atom, it contains most of the mass of the atom as well as protons and neutrons.
Why are atoms neutral despite having charged particles?
Because atoms have equal numbers of electrons and protons, and because these subatomic particles have equal but opposite charges.
What is a chemical element?
a chemical element ia a pure substance that consist entirely of one type of atom
What does an element's atomic number represent?
It represents how many protons and electrons there are.
Atoms of the same element that differ in the number of neutrons they contain are known as?
isotopes
How are isotopes identified?
Isotopes are identified by their mass number
Why do all isotopes of an element have the same chemical properties?
Chemical properties are determined by the number of protons and electrons an atom of an element has. An isotope only differs in the number of neutrons it has. All isotopes of an element have the same atomic number (the number of electrons/protons), therefore, they have the same number of electrons/protons and therefore similiar chemical properties.
What is a chemical compound?
A substance formed by the chemical combination of two or more elements in definite proportions
What does the formula for table salt indicate about that compound?
The formula for table salt, NaCl, indicates that the elements from which table salt forms-sodium and chlorine-combine in a 1:1 ratio.
What holds atoms in compounds together?
Chemical Bonds
How is a covalent bond and ionic bonds formed?
a convelent bond is formed when electrons are shared between atom. an ionic bond is formed when one or more electrons are transferred from one atom to another
What is an ion?
An ion is if an atom loses or gains an electron it now has a new charge and is called an ion. The electron is responsible for creating ions because it creates a new charge if it is lost or gained. See how many more or less electrons there are than protons. More electrons are a negative charge, while less electrons is a positive charge.
The slight attraction that develop between oppositly charged regions of nearby molecules are called?
Chemists call such intermolecular forces of attraction van der Waals forces after the scientist that discovered them.
The structure that results when atoms are joined together by covalent bonds is called a(an)?
The molecule is the smalles unit of most compounds.
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