 # Physical Science Chapter 4.

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Physical Science Chapter 4

Atoms The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons

Atoms

History of the atomic theory

What is an Atom

The parts of the atom are called subatomic particles
Protons, electrons, and neutrons are subatomic particles

Positively charged particles found in the nucleus
Protons Positively charged particles found in the nucleus Each proton has a charge of 1+ Some nuclei have more than 100 protons

Protons

Discuss a scientific observation you made this weekend,
Bellwork 9-30 Discuss a scientific observation you made this weekend, Then…draw an atom with all of its subatomic particles from memory

Negatively charged particles found in the space outside the nucleus
Electrons Negatively charged particles found in the space outside the nucleus Each electron has a charge of -1

Electrons

A neutral particle found in the nucleus of an atom
Neutrons A neutral particle found in the nucleus of an atom Its mass is almost exactly equal to a proton

Neutrons

Properties of particles
Protons, electrons, and neutrons can be distinguished by mass, charge, and location in an atom

Protons and neutrons have almost the same mass
Takes almost 2000 electrons to equal the mass of one proton Electron’s charge, however, is equal to that of the proton

Periodic table

Atomic Mass and Number

Atomic Number Atomic number of an element equals the number of protons in an atom of that element

The atomic number also equals the amount of electrons and atom has
Atoms are neutral because they have the same number of electrons and protons Therefore… The atomic number also equals the amount of electrons and atom has

Atomic number gives the number of protons, nut not the # of neutrons
Mass Number Atomic number gives the number of protons, nut not the # of neutrons Mass number is the sum of the protons and neutrons

Atom of aluminum has 13 protons and 14 neutrons, what is its mass number?

Dalton thought that all atoms of a given element were identical
Isotopes Dalton thought that all atoms of a given element were identical Every atom of a given element does have the same amount of protons and electrons,

Isotopes But every atom of a given element does not have the same number of neutrons Isotopes are atoms of the same element that have different numbers of neutrons and different mass numbers

What are some effects of water water that contains hydrogen isotopes?
Look at figure 12 on page 112 What are some effects of water water that contains hydrogen isotopes?

With a group of 2-3 1. How are the compositions of heavy water and ordinary water similar? What type of hydrogen atoms does ordinary water contain? What type of hydrogen atoms does heavy water contain? Compare the properties of heavy water and ordinary water.

Complete section one and 2 in your workbook
When complete… Complete section one and 2 in your workbook What you do not finish in class will be homework

Bellwork How many neutrons are in an atom with an atomic number of 32 and an atomic mass of 68?

Bohr Bohr’s model of the atom focused on the electron which is what makes his model the modern model

Energy Levels Electrons move with constant speed in fixed orbits around the nucleus Each electron has a specific amount of energy Sometimes atoms gain or lose energy and the energy in an electron can change

Energy Levels Energy levels: The possible energies that an electron can have. The electrons in an atom can move from one energy level to another when they gain or lose energy

How do we know? Scientists can measure the energy gained when electrons absorb energy and move to a higher energy level They can also measure the energy released when an electron moves to a lower energy level

How do we know? Some elements emit light when they release energy Explosions can cause heat which pushes electrons to higher energy levels

Electron cloud The electron cloud model is used to describe the possible locations of electrons around the nucleus.

Atomic Orbitals Orbital is the region of space around the nucleus where the electron is likely to be