Hon Chem Unit 2 Ch 4 & 6 Isotopes, Periodic Table

The law of conservation of mass states that:

• Matter can be created and destroyed.
• Matter can be created but not destroyed.
• The products of a reaction always have a greater mass than the reactants.
• The products of a reaction must have the same mass as the reactants.

Dalton’s theory also conveniently explained what?

• the electron
• law of conservation of mass
• the nucleus
• law of Democritus

Atoms are mostly ____.

• postive
• solid spheres
• negative
• empty space

An unknown element has 19 protons, 19 electrons, and 3 isotopes with 20, 21 and 22 neutrons. What is the element’s atomic number?

• 38
• 19
• 40
• unable to determine

Rutherford's gold foil experiment confirmed that an atom has 

• a very dense nucleus.
• positive charges spread throughout.
• no negative particles.
• neutrons.

How many neutrons does uranium-235 have?

• 238
• 92
• 146
• 143

Tags

NGSS.HS-PS1-8

What are the two fundamental subatomic particles found in the nucleus?

• proton and electron
• proton and neutron
• neutron and electron
• neutron and positron

Elements with the same number of protons and differing numbers of neutrons are known as what?  

• isotopes
• radioactive
• abundant
• ions

In the modern periodic table elements are arranged by:

• atomic mass
• atomic number
• valence electrons
• number of isotopes

Each column in the periodic table is called a 

• period
• group
• cluster
• unit