Biology Test 9/28/23

Observation

The act of noticing and describing events or processes in a careful, orderly way

Inference

Logical interpretations based on what is already known 

Hypothesis

A scientific explanation for a set of observations that can be tested 

Controlled experiment

Testing a hypothesis with only one variable changed. All other variables should be kept unchanged or controlled

• It is important to control variables because if several variables are changed in the experiment, researchers cannot easily tell which variable is responsible for the results

Conclusion

You may want to change your hypothesis based on your findings if you see its incorrect, and you should make a graph. Independent variable is always the x not the why on the graph. You need to do the experiment multiple times to make sure it is right

Theory

What you get out of the conclusion

Independent Variable

Manipulated by the scientists

Dependent Variable

The result of the independent variable 

Atoms

An atom is the smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element.

• What they are made of

An atom is made up of protons, neutrons, and electrons

Protons

Massive, has a positive charge of +1 and is heavy, only protons can change the atom

neutrons

Massive, neutral charge of 0 mass is +1, stabilize/holds together the atom

Electrons

 Negative charge, really tiny/light charge of -1

Atomic Number

The number of protons, determines the order of the periodic table of elements

• A Chemical element is one type of atom thats is distinguished by its atomic number, which is the number of protons in its nucleus 

Atomic Mass

Protons and neutrons together, the mass of an atom

Isotopes

Atoms that have the same number of protons but a different number of neutrons

Ions

An atom with a whole charge. An uneven number of protons, usually when you combine a Non metal and a Metal 

The charge of an ion=number of protons - the number of electrons 

Protons cannot be removed or added it is only the electrons that is are added or removed and create the charge

Charges

Protons and electrons: Balance each other

Ex: Elemental sodium has protons and eleven electrons: 11+-11= 0

If sodium were to lose one electron, sodium would have a net positive charge. If chlorine were to gain an electrons, it would have a negative charge 

An atom becomes positively charged when another becomes negatively charged and these charge  differences create an attractive force between an atom known as a bond 

Ionic Bonds

When one atom steals an electron from another atomś outer shell

• An atom becomes positively charged when while another atom becomes negatively charged and these charge differences create an attractive force between the atoms know as a bond 

Covalent Bonds

• Covalent Bonds: 

• Sometimes atoms share share electrons

• A bond inwhich electrons are shared between atoms 

• Form molecules

• Usually between non-metals 

• Goal: to get complete valence shell (Usually 8) by sharing

• Ex: H20

The Octec

• Atoms tend to combine in such a way that they each have 8 electrons in their outer shell

• Doesn´t apply to helium bc it is stable