This 45-foot-tall steel sculpture is made of 10 tons of steel. If a proton had the same mass as the sculpture, then an electron would have a mass of about 5 kilograms.
4.2 The Structure of an Atom
What are three subatomic particles?
Properties of Subatomic Particles
1. Protons, electrons, and neutrons are subatomic particles.
4.2 The Structure of an Atom
Protons
Based on experiments with elements other than gold, Rutherford concluded that the amount of positive charge varies among elements.
2. A proton is a positively charged subatomic particle that is found in the nucleus of an atom. Each proton is assigned a charge of 1+. Each nucleus must contain at least one proton.
Properties of Subatomic Particles
4.2 The Structure of an Atom
Electrons
The particles that Thomson detected were later named electrons.
An electron is a negatively charged subatomic particle that is found in the space outside the nucleus. Each electron has a charge of 1−.
Properties of Subatomic Particles
4.2 The Structure of an Atom
Neutrons
In 1932, the English physicist James Chadwick carried out an experiment to show that neutrons exist. 3. Chadwick concluded that the particles he produced were neutral because a charged object did not deflect their paths.
A neutron is a neutral subatomic particle that is found in the nucleus of an atom. It has a mass almost exactly equal to that of a proton.
Properties of Subatomic Particles
4.2 The Structure of an Atom
What properties can be used to compare protons, electrons, and neutrons?
Comparing Subatomic Particles
4. Protons, electrons, and neutrons can be distinguished by mass, charge, and location in an atom.
4.2 The Structure of an Atom
Everything scientists know about subatomic particles is based on how the particles behave in experiments. Scientists still do not have an instrument that can show the inside of an atom.
Use Data Table below to answer 5
Comparing Subatomic Particles
4.2 The Structure of an Atom
Here are some similarities and differences between protons, electrons, and neutrons.
Comparing Subatomic Particles
4.2 The Structure of an Atom
How are atoms of one element different from atoms of other elements?
Atomic Number and Mass Number
Atoms of different elements have different numbers of protons.
4.2 The Structure of an Atom
Atomic Number
Atomic Number and Mass Number
4.2 The Structure of an Atom
9 Each element has a different atomic number. A The atomic number of sulfur (S) is 16. �B The atomic number of iron (Fe) is 26. �C The atomic number of silver (Ag) is 47.
Atomic Number and Mass Number
4.2 The Structure of an Atom
8 Atoms are neutral, so each positive charge in an atom is balanced by a negative charge. That means the atomic number of an element also equals the number of electrons in an atom of that element.
Atomic Number and Mass Number
4.2 The Structure of an Atom
Mass Number
10 The mass number of an atom is the sum of the protons and neutrons in the nucleus of that atom. To find the number of neutrons in an atom, you need the mass number of the atom and its atomic number.
Use this formula for 11�
The atomic number of aluminum is 13. An atom of aluminum that has a mass number of 27 has 13 protons and 14 neutrons
Atomic Number and Mass Number
4.2 The Structure of an Atom
What is the difference between two isotopes of the same element?
12 Isotopes: Neutral so that means the _________ = _________.
13 Isotopes of an element have the same atomic number but different mass numbers because they have different numbers of neutrons.
4.2 The Structure of an Atom
14 Isotopes are atoms of the same element that have different numbers of neutrons and different mass numbers.
15 To distinguish one isotope from another, the isotopes are referred by their mass numbers. For example, oxygen has 3 isotopes: oxygen-16, oxygen-17, and oxygen-18.
16 All three oxygen isotopes can react with hydrogen to form water or combine with iron to form rust.
Isotopes
4.2 The Structure of an Atom
With most elements, it is hard to notice any differences in the physical or chemical properties of their isotopes. Hydrogen is an exception.
Hydrogen-1 has no neutrons. (Almost all hydrogen is hydrogen-1.) Hydrogen-2 has one neutron, and hydrogen-3 has two neutrons. Because a hydrogen-1 atom has only one proton, adding a neutron doubles its mass.
Isotopes
4.2 The Structure of an Atom
17 Water that contains hydrogen-2 atoms in place of hydrogen-1 atoms is called heavy water. Hydrogen-2 atoms have twice the mass of hydrogen-1 atoms, so the properties of heavy water are different from the properties of ordinary water.
Isotopes
4.2 The Structure of an Atom
Assessment Questions
4.2 The Structure of an Atom
Assessment Questions
4.2 The Structure of an Atom
�
Assessment Questions
4.2 The Structure of an Atom
�ANS: F, electron
Assessment Questions
4.2 The Structure of an Atom