Regents Review

Which statement describes the structure of an atom?

• The nucleus contains positively charged electrons.
• The nucleus contains negatively charged protons.
• The nucleus has a positive charge and is surrounded by negatively charged electrons.
• The nucleus has a negative charge and is surrounded by positively charged electrons.

Which term is defined as the region in an atom where an electron is most likely to be located?

• nucleus
• orbital
• quanta
• spectra

What is the number of electrons in an atom of scandium?

• 21
• 24
• 45
• 66

Which particle has the least mass?

• a proton
• an electron
• a helium atom
• a hydrogen atom

Which electron transition in an excited atom results in a release of energy?

• first shell to the third shell
• second shell to the fourth shell
• third shell to the fourth shell
• fourth shell to the second shell

On the Periodic Table, the number of protons in an atom of an element is indicated by its

• atomic mass
• atomic number
• selected oxidation states
• number of valence electrons

Which type of formula shows an element symbol for each atom and a line for each bond between atoms?

• ionic
• structural
• empirical
• molecular

What is conserved during all chemical reactions?

• charge
• density
• vapor pressure
• melting point

In which type of reaction can two compounds exchange ions to form two different compounds?

• synthesis
• decomposition
• single replacement
• double replacement

At STP, two 5.0-gram solid samples of different ionic compounds have the same density. These solid samples could be differentiated by their

• mass
• volume
• temperature
• solubility in water