Presentation on theme: "Atoms This goes in the Chemistry section of your binder."— Presentation transcript:
Atoms This goes in the Chemistry section of your binder.
An atom is the smallest particle of an element that has the chemical properties of that element.
A single atom is not visible to the eye. Therefore most substances are made of millions or billions of atoms.
The element Hydrogen (H) #1 on the periodic table, accounts for 90% of the total mass of the universe.
Only 1% of the atoms on Earth are Hydrogen (H) and most of those are combined with oxygen to form water, H 2 O
Look at the circle graph on page D 10. Answer the ?s in your notes.
1. How does the Oxygen (O) on Earth compare the O in humans? 2. What element is the 2 nd highest in humans? On Earth? 3. Why do you think there is a higher percentage of (H) in the human body than on Earth? 4. Humans are mostly composed of what 4 elements? 5. Earth is mostly composed of what 4 elements?
Atoms are made of smaller particles (sub-atomic); electrons protons neutrons
Match the charge with the particle: (+) electron (N) neutral proton (-) neutron
A proton is a positively charged particle. A neutron is an uncharged particle. Where are both particles located in an atom?
Neutrons and protons have approximately the same mass. (+) and (N) are grouped together in the center of an atom, called the nucleus.
Electrons are negatively charged particles that move around the nucleus. (-) are much smaller than protons, they are 1/2000 of a proton or neutron. (-) move around the nucleus of an atom so quickly their exact positions cannot be determined. Therefore (-) are considered a “cloud” around the nucleus.
Electrons are attracted to the positively charged protons. Atoms that have = numbers of protons and electrons are said to be neutral.