Flashcards in Chapter 2 - Chemical Level Deck (148)
What is chemistry?
The science of the structure and interactions of matter
What is matter?
Anything that occupies space and has mass
What is mass?
Is the amount of matter in any object
Does not change
What is weight?
The force of gravity acting on matter
Matter exists in what three states?
1. Solid - definite shape and volume
2. Liquid- definite volume and assume the shape of its container
3. Gas - neither definite shape nor volume
What are chemical elements?
Building blocks of all living and non living things.
Cannot be split into simpler substances by ordinary chemical means
What are the 4 major elements?
Oxygen (o), carbon (c), hydrogen (h), and nitrogen (n)
What are atoms?
The smallest unit of matter that retains the properties and characteristics of the element
(Each element is made up of atoms)
What is the nucleus of an atom?
The dense central core of the atom.
A subatomic particle.
What is the nucleus made of (in atoms)?
1. Neutrons - no charge
2. Protons - positive charge
What are electrons?
Tiny, negatively charged particles that float around the nucleus, do not follow a fixed path or orbit but form a "cloud"
How many electrons can each shell house?
First shell - 2
Second shell - 8
Third shell - 18
18 in each shell after that.
An atom has the same number of what?
Protons (+) and electrons (-)
Which means that it doesn't have an electrical charge, each atom is neutral.
What determines an atoms atomic number?
Number of protons
What is the mass number?
Sum of its protons and neutrons.
Example: sodium has 11 protons and 12 neutrons, therefore the mass number is 23
What is an isotope?
Atoms of the same element that have different numbers of neutrons and therefore different mass numbers.
They have the same chemical properties because they have the same number of protons and electrons.
What is a radioactive isotope?
Some isotopes are unstable; their nuclei decay (spontaneously change) into a stable condition.
As they decay, they emit radiation
What is half-life?
The time required for an isotope for half of the radioactive atoms in the sample of that isotope to decay into a more stable form.
What is the standard unit of measurement for measuring the mass of atoms?
Daltons (atomic mass unit, amu)
What is the atomic mass or atomic weight?
The average mass of all of its naturally occurring isotopes
What is an ion?
Is an atom that has a positive or negative charge b/c it has an unequal number of protons and electrons
What is ionization?
The process of giving up or gaining electrons
What is a molecule?
A combination of two or more atoms sharing electrons
What is a compound?
A substance that contains atoms of two or more different elements, examples: water, sodium chloride
The molecule of oxygen is NOT a compound because it only has one element
What is a free radical?
An atom or a group of atoms with an unpaired electron in the outermost shell
Highly unstable, highly reactive and destructive to nearby molecules
May break apart important body molecules
What are chemical bonds?
The force that holds together the atoms of a molecule or a compound
What is the valence shell?
The outermost shell
What determines whether or not an atom will form a chemical bond?
The number of electrons in its valence shell.
8 - is stable, will not bond
7 - bonds easily, room for one electron
What is the octet rule?
One atom is more likely to interact with another if doing so leaves both with 8 valence electrons