Atoms and Its Structures

Which phrase describes an atom?
 

• a positively charged electron cloud surrounding a positively charged nucleus
• a positively charged electron cloud surrounding a negatively charged nucleus 
• a negatively charged electron cloud surrounding a positively charged nucleus
• a negatively charged electron cloud surrounding a negatively charged nucleus

Which statement concerning elements is true?

• Different elements must have different numbers of isotopes. 
•  Different elements must have different numbers of neutrons.
• All atoms of a given element must have the same atomic number.
• All atoms of a given element must have the same mass number.

If the atomic mass number of an atom is 35, which statement is most accurate? 

• The atom is not an isotope. 
• The atomic number is less than 17.
• The atom has an odd number of neutrons.
• The number of protons does not equal the number of neutrons.

How many protons does an atom with an atomic number of 23 and a mass number of 51 have? 

• 23
• 51
• 28
• 74

Which of the following determines the identity of an element? 

• overall charge
• atomic mass
• mass number
• atomic number

Isotopes exist because atoms of the same element can have different numbers of 

•  protons.
•  electrons.  
• neutrons. 
• None of the options apply.

Which total mass is the smallest? 

• the mass of 2 electrons
• the mass of 2 neutrons 
• the mass of 1 electron plus the mass of 1 proton
• the mass of 1 neutron plus the mass of 1 electron

An atom is electrically neutral because the 

• number of protons equals the number of electrons 
• number of protons equals the number of neutrons 
• number of neutrons are greater than protons plus electrons
•  ratio of the number of neutrons to the number of electrons is 1:1 

A particle of an atom contains 26 protons, 23 electrons, and 56 neutrons. What will be the correct atomic number for this particle? 

• 26
• 23
• 33
• 56

Which element could have a mass number of 86 atomic mass units and 49 neutrons in its nucleus?

• In
• Rb
• Rn
• Au