Electrons fill subshells in order of increasing atomic number (Z). Each orbital can hold only two electrons following Pauli exclusion principle. Electrons fill lower-energy subshells before higher-energy ones
Python raises exceptions when code encounters problems. IndexError occurs when indexing lists/tuples incorrectly. KeyError arises when accessing non-existent dictionary items. SyntaxError appears when using reserved keywords or forgetting parentheses. TypeError happens when functions receive incompatible data types
TSCA regulates chemicals and substances in articles since 1976. EPA administers substance restrictions and reporting requirements. TSCA Inventory contains 86,607 chemicals updated every six months
French articles are le, l', la, and les for specific nouns. Articles are used with verbs expressing tastes like aimer and préférer. Articles are needed before non-count nouns, abstract concepts, and languages. Articles are used with dates and regular events
Exception handling prevents program crashes by responding to errors. Errors are serious issues that should not be handled. Exceptions are less severe and can be managed by the program
Error and Exception are subclasses of Throwable class. Only Throwable instances can be thrown by JVM or caught. Both types include stack trace information