Chapter 2: The Nature of Molecules and the Properties of Water Flashcards
Matter
any substance that has mass and occupies space
Mass
the amount of a substance
Atom
small particles that make up matter
Weight
the force gravity exerts on a substance
Atomic number
number of protons in an atom
Atomic mass/weight
sum of the masses of its protons and neutrons
What are the masses of atoms and subatomic particles measured in?
Daltons
Cation
atom with more protons than electrons with net + charge
Anion
atom with less protons than electrons with net - charge
Ion
- atoms where the number of protons is not the same as the number of electrons
- gain or loss of electrons
Proton
- positive
- found in nucleus
- 1 dalton
Neutron
- neutral
- found in nucleus
- 1 dalton
Electron
- negative
- orbit nucleus in energy levels
- negligible mass
Isotope
atoms of a single element with different number of neutrons
ex) Carbon-12 (stable) , Carbon-13 (stable) , Carbon-14 (radioactive) - used to determine ages of fossils
Radioactive decay
nucleus of an atom breaks up into elements with lower atomic numbers and releases energy
Orbital
regions where electrons are likely located
Energy levels
- outer levels have more energy
- 1st level with 1 orbital: holds 2 electrons
- 2nd level with 4 orbitals: holds 8 electrons
- 3rd level can hold 18 electrons
Chemical behavior
- based on valence electrons
- complete valence shell = nonreactive
- incomplete valence shell = chemically reactive
Octet rule
atoms tend to establish completely full outer energy levels
Molecule
- made up of two or more atoms of the same or different elements bonded together
- ex) O2
Compound
- two or more different elements bonded together
- ex) H2O
What four elements make up 96% of living matter?
carbon, oxygen, hydrogen, and nitrogen
Periodic table trends
- elements up and down have same number of electrons in outer shells
- atoms are electrically neutral
Chemical bonds
join molecules together