2.1 Atoms and Reactions

• What are atoms composed of?

  Atoms are composed of subatomic particles.
• Why are atoms mostly made up of empty space?

  Because the mass is concentrated in the nucleus.

  
• Where is the mass of an atom concentrated?

  The mass of an atom is concentrated in the nucleus.
• What subatomic particles are found in the nucleus?

  The nucleus contains neutrons and protons.
• What is the charge of the nucleus?

  The nucleus is positively charged.
• What do negatively charged electrons create around the nucleus?

  They create a 'cloud' of negative charge.
• What holds an atom together?

  The electrostatic attraction between the nucleus and electrons holds an atom together.
• How are ions formed?

  Ions are formed when atoms gain or lose electrons.
• What is the overall charge of a neutral atom?

  A neutral atom has no overall charge.
• What determines the element of an atom or ion?

  The atomic number determines which element it is.
• How many protons does lithium have?

  Lithium has 3 protons.
• How many protons does beryllium have?

  Beryllium has 4 protons.
• How can the number of protons of an unknown element be calculated?

  By using its mass number and number of neutrons.
• What is the formula to calculate the number of protons?

  Number of protons = mass number - number of neutrons.
• How many protons does a magnesium ion have?

  A magnesium ion has 12 protons.
• How many protons does a carbon atom have?

  A carbon atom has 6 protons.
• How many protons does element X have if its mass number is 63 and it has 34 neutrons?

  Element X has 29 protons.
• How many electrons does a neutral atom have?

  A neutral atom has the same number of electrons as protons.
• What is a cation?

  A cation is a positively charged ion that has lost electrons.
• What is an anion?

  An anion is a negatively charged ion that has gained electrons.
• How many electrons does a magnesium ion with a 2+ charge have?

  A magnesium ion has 10 electrons.
• How many electrons does a neutral carbon atom have?

  A neutral carbon atom has 6 electrons.
• How many electrons does element X have if it has 29 protons?

  Element X has 29 electrons.
• How can the number of neutrons in an atom be calculated?

  Number of neutrons = mass number - number of protons.
• How many neutrons does a magnesium ion with a mass number of 24 have?

  A magnesium ion has 12 neutrons.
• How many neutrons does a carbon atom with a mass number of 12 have?

  A carbon atom has 6 neutrons.
• How many neutrons does element X have if it has a mass number of 63 and 29 protons?

  Element X has 34 neutrons.
• What are isotopes?

  Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
• How are isotopes represented?

  Isotopes are represented by the chemical symbol followed by a dash and the mass number.
• What are two examples of isotopes of carbon?

  Carbon-12 and carbon-14.
• Why do isotopes have the same chemical properties?

  Because they have the same number of electrons in their outer shells.
• What physical properties differ among isotopes?

  Isotopes have different masses and densities.
• What is the standard for relative mass of an atom?

  The carbon-12 isotope is the international standard.
• What is the fixed mass of a carbon-12 atom in atomic mass units?

  The mass of a carbon-12 atom is fixed as exactly 12 atomic mass units.
• What is relative isotopic mass?

  Relative isotopic mass is the mass of an isotope relative to 1/12 of a carbon-12 atom.
• How is the relative atomic mass of an element calculated?

  By using the weighted mean of the isotopes' masses and their relative abundances.
• What does the relative atomic mass represent?

  The relative atomic mass represents the average mass of an atom relative to 1/12 of the mass of a carbon-12 atom.
• What is the process of mass spectrometry?

  Mass spectrometry involves vaporizing a sample, ionizing it, accelerating ions, and detecting them.
• What does the mass-to-charge ratio indicate in mass spectrometry?

  The mass-to-charge ratio indicates the mass of ions relative to their charge.

  
• How is the relative atomic mass of an element determined using mass spectrometry?

  By analyzing the mass spectrum and calculating based on the abundance of isotopes.