Common Sense Knowledge for questions

• Particles surrounding the nucleus are ALWAYS electrons
• Mass of each proton and each neutron is equal to = 1 u
• the further the nucleus the more energy
• When the atom moves from the ground to excited state the atom ALWAYS absorbs energy.
• In terms of chemical property ALWAYS think of reactivity
• Different properties ALWAYS results in different structures
• Matter can be either Pure or Mixed substance
• Pure substance: Element or a compound
• Mixed Substance: Heterogenous or Homogenous
• In a compound there's ALWAYS a definite ratio
• In a mixture(mixed) its ALWAYS the proportions change
• structural formula has to do with how the atoms are arranged
• empirical formula has to do with how atoms are reduced
• molecular formula is all about which atoms are in the molecule
• Different elements ALWAYS has different masses!!!
• A multiple covalent bond usually but never has any lone pairs
• When a bond is formed energy is released
• When a bond is broken energy is absorbed
• Heat flows from warmer to colder
• An ideal gas ALWAYS has particles with no attractive forces
• chemical systems at equilibrium ALWAYS have equal rates of forward and reverse reactions
• In a heat of reaction for a chemical change its ALWAYS:

  products - reactants
• Entropy - getting disordered
• Systems in nature tend to change towards lower energy and greater disorder
• Electrolytes are ALWAYS acids, bases, and salts
• Nonelectrolytes are ALWAYS covalent/molecular
• Acids donate hydrogen ions
• Nuclear Reactions always produce a huge amount of energy
• Diatomic Elements: BrINClHOF
• the less electrons the small the radius
• In terms of electrons + means you lost e-, - means you gained e-
• Compounds CAN be broken down by a chemical change
• Elements that are SINGLE CANNOT be broken down by a chemical change
• Compare: <, =, >
• Constant: Remains the same
• When pressure goes up, volume goes down
• Physical change requires chemical formulas for elements/atoms to ALWAYS be the same
• A powdered reactant is much faster than a strip of a reactant
• A redox reaction has single elements that are combined
• pH can only change by factors of 10 when increasing or decreasing