What is chemistry?
Chemistry is the study of matter
What is matter?
M - is a substance that has mass and volume
What is a substance?
Substance is any material, all samples of which have the same composition and properties. Substance is composed of atoms, and it can't be separated into elements by physical means, only by breaking bonds between atoms.
What is an example of not a substance?
Mixture is not a substance
What is the matter made of?
All matter is made of atoms, and the properties of matter can be explained by atoms making it up.
What is an atom? And what are its subanatomic particles?
- Atom is the smallest unit of an element that still retains properties of an element.
- Subanatomic particles:p, n, e
How are electrons arranged?
Electrons are found outside of nucleus and are arranged according to their energy level
Classification of matter?
- 1) Pure substance (composed of only one type of atom or molecule), each atom in the molecule present in the same ration : NaCl
- It shows the same properties
- 2)Mixture (compose of more than one type of atom or molecule, and can be physically separated into it's component substances)
- ** homogenous (solutions)
How do we identify an element?
By it's symbol and atomic #.
What is an atomic # and mass #?
- Atomic # is equal to the # of p in the nucleus.
- Mass # = number of nucleons (p+n)
What is the charge of an element?
- Element is usually neutral.
- Number of protons = number of e
How to find the number of neutrons?
n = Mass # - Atomic #
- Sometimes an element can be found with different mass numbers => they have the same number of protons but different # of N
Atomic mass is a weighted average of the mass numbers of naturally occurring isotopes of an element
Isotopes that are radioactive (their nuclei are unstable and produce E by emitting radiation in form of A, B, G rays)
How do we treat thyroid cancer?
By using Iodine -131 (radio-isotope)
- ions are charged atoms:
- + cations
- - anions (has more e than p)
Energy level of an electron. Valence electrons
- Electrons are found at different energy levels. Electrons found in the outermost energy level called valence electrons.
- Small atoms have 2 VE
- All other may have max of 8 VE
periodic table: periods, groups, metals,
- Periodic table contains elements.
- Periods= rows, in order of increasing atomic #
- Groups = columns, contain elements with similar properties b/c of the same electron configuration.
- From right to left:
- Metals=> metalloids=>Non-Me=>Noble Gases
have full valence shell and are inert, there are many more Me than nonMe