Resumen Ciencias Naturales Septimo Basico(Ingles)

Resumen Naturales
What is matter? = Is everything that has volume and mass
What is volume? = Amount of space an object takes.
Cubic centimeters are for 3-D shapes, square centimeters are not.
What is matter? = Is everything that has volume and mass
What is volume? = Amount of space an object takes.
Cubic centimeters are for 3-D shapes, square centimeters are not.5*3*3 = 15*3 = 45
To measure regular shape’s volume you multiply the length, width, height.
To measure irregular-shape’s volume we use a graduated cylinder or beaker with water, for example with 55ml of water and then drop the irregular shape in. Then we have, for example, 65ml, so our shape measures 10ml.

Atom stucture
Protons = positive chargeand neutrons = no charge
Protons = positive charge and neutrons = no charge
Electron = negative charge
Electron = negative charge

Only electrons can move to other objects because they are at the outside, spinning around.
Atoms with charge have more electrons or protons. This are named Ions.
Atoms with no charge have the same number of electrons and protons
Cation: Positive ION (moreprotons than electrons)
Anion: negative ION (more electrons than protons)


The atomic mass is the sum of protons and neutrons. For example carbon :

Has an atomic mass of 12.

The atomic number is the number of protons in the atom. For example carbon:
Has an atomic number of 6 protons.

Elements
Elements are pure substances, they cannot be dividedinto simpler substances by physical or chemical changes. There is only one particle. Each element has it’s own characteristics that allows us to identify them, this properties do not depend in the amount of material.
Every element will have a determinated number of protons, but it may change in number of electrons, determinating if it’s an ION. It also may change in number of neutrons, then we callit an isotope.
Atomic number Protons: 1 Neutrons:0 electrons:1
Chemical symbol (hydrogen) Like this element doesn’t have any charge, we assume that it has the same number of protons.
Atomic mass

1
1
The + sign means it has a positive ION, but we can’t change the number ofprotons, so we change the number of electrons.

P=5
N=5
E=4
-2
-2
The – sign means it is a negative ION, so we change the number of electrons:
P=7
N=7
E=9

Chemical formulas and chemical reactions
2
2
H O Subscript (shows how mary, in this case, hygrogen we have.)
The capital letters tell us there is a new element.
6
6
12
12
6
6
3 C H OCoefficient: C=3*6 H=3*12 O= 3*6

2
2
3
3
4
4
Al (SO ) affects all formula in parenthesis
Chemical reaction = process by wich one or more substances undergo to produce one or more different substances. Has two parts, the reactants and the products. The reactance are going to be part of a chemical reaction and the substances that we obtain are named products. The chemical reactionmust be ruled by the law of conservation of mass wich tells us nothing is created or destroyed, only transformed.
EX.
A B

AB C

2
2
2H + O = H O
Example:
We have to balance them. So hydrogen is not correct cause there is one hydrogen more. And nitrogen is not correct cause there is one missing. So we have to make the “happy” by making them have the same number of nitrogen andhydrogen in the reactants and in the product.
1st = Let’s find the least common multiple for hygrogen, in this case is 6, so we multiply time 3 in the reactants and by 2 in the product. So we have hydrogen happy
2nd = we also affected nitrogen in the 1st step, so we have nitrogen happy too.
N2+3H2 2NH3
Reactants | Products |
N = 2 | N = 1×2=2 |...