atomic structer

• What are atoms considered to be the building blocks of?

  All matter
• What is located at the center of an atom?

  A tiny, dense, positively charged nucleus
• How do electrons behave in relation to the nucleus?

  They orbit around the nucleus
• How much smaller is the radius of the nucleus compared to the whole atom?

  Over 10,000 times smaller
• What does the nucleus contain?

  Protons and neutrons
• What is the relative atomic mass of protons and neutrons?

  One unit
• What is the charge of neutrons?

  No charge
• What is the charge and mass of electrons?

  Negative charge with almost no mass
• What is the radius of an atom?

  $1 \times 10^{-10} \text{ m}$
• How many atoms can fit side by side across a thumbnail?

  About one hundred million
• What is a molecule?

  A group of bonded atoms
• What is a water molecule comprised of?

  Two hydrogen atoms and one oxygen atom
• What is relative mass used for?

  Comparing particles
• What is the charge of a positron?

  Positive charge
• What is the mass of one atomic mass unit (amu)?

  $1.67 \times 10^{-27} \text{ kg}$
• How is a positron produced?

  During nuclear beta-plus decay
• How long do positrons exist under normal conditions?

  A fraction of a second
• What happens when a positron reacts with an electron?

  They are destroyed
• Why is the total charge within an atom zero?

  Electrons equal the number of protons
• How many protons, neutrons, and electrons does a Lithium atom have?

  Three protons, four neutrons, three electrons
• What happens if an atom loses electrons?

  It is said to be ionised
• What is the atomic number of an atom?

  The number of protons
• How are elements in the periodic table ordered?

  By their atomic number
• What is the atomic number of Hydrogen?

  1
• What is the atomic number of Sodium?

  11
• What is the atomic number of Uranium?

  92
• What does the mass number represent?

  Total number of protons and neutrons
• How can the number of neutrons be found?

  Mass number minus atomic number
• If a sodium atom has a mass number of 23 and an atomic number of 11, how many neutrons does it have?

  12
• What are isotopes?

  Atoms with the same protons but different neutrons
• How many isotopes does Hydrogen have?

  Three
• Do isotopes affect the chemical properties of an atom?

  No, only their mass is affected
• Why is Chlorine's mass number given as 35.5?

  It has two isotopes with different masses
• What remains the same in different isotopes of an element?

  The number of protons and electrons
• What can cause some isotopes to be unstable?

  An imbalance of protons and neutrons
• What do electrons in an atom orbit around?

  The nucleus
• What are energy levels in an atom?

  Particular distances where electrons orbit
• How many electrons can occupy the first energy level?

  Two electrons
• How many electrons can fit in the second and third energy levels?

  Eight electrons each
• What happens to electrons in higher energy levels?

  They have greater potential energy