Understanding Matter: Properties, Composition, and Atomic Structure
Pure Substances and Mixtures
Pure substances are composed of particles that are identical.
- Simple Substances: These cannot be broken down into simpler substances by chemical methods. Their atoms are all the same (e.g., iron, gold, copper, chlorine).
- Composite Substances: These are formed by the union of two or more chemical elements in a fixed proportion. They can be separated into their constituent elements by simple chemical methods (e.g., water, sodium chloride).
Mixtures are combinations of two
Read MoreEnglish Learning Exercises: Greetings, Numbers, Verbs
Answer the Following Questions About Yourself
A. What’s your name?
My name is Jose Alberto Alvarez Olivo.
B. How are you?
I’m fine, thanks.
C. How old are you?
I am 23 years old.
D. Where are you from?
I am from the Dominican Republic.
E. Where do you live?
I live in San Francisco de Macoris.
Write 5 Formal or Informal Greetings in English
- A. Good afternoon, how are you?
- B. Good morning, how did you sleep?
- C. How are you doing?
- D. How’s your day going?
- E. Nice to meet you.
Write the Following Cardinal Numbers in
Read MoreElectric Charges, Energy Sources, and Power Generation
Electric Charges: Positive and Negative
There are two kinds of electric charges: positive charge (+) and negative charge (-).
- The closer two objects carrying the same sign are, the more they repel each other.
- The closer two objects with different signs of charge are, the more they attract each other.
- A body with no electrical charge has the same number of protons as electrons.
- A body with a negative electric charge has gained electrons.
- A body with a positive electric charge has lost electrons.
Conductors
Read MoreAtomic Models: Rutherford to Quantum Mechanics
Rutherford Model
The atom has a small, central nucleus with a positive electric charge, containing nearly all of the atom’s mass. Electrons with negative electric charge orbit the nucleus in long-distance circular paths. The electrical attraction between electrons and the nucleus provides the centripetal force for this revolution. The sum of the negative charges of the electrons equals the positive charge of the nucleus, making the atom electrically neutral.
Bohr Atomic Model
Postulate 1: Electrons
Read MoreBiochemistry and Biophysics: Fundamentals of Life’s Chemistry
Biochemistry and Biophysics: The Chemistry of Life
Biochemistry and biophysics are the sciences that deal with the basic chemistry of life. The objective is to study the chemical composition of living beings, the relationships between their chemical compounds, their transformations, regulation, and how these transformations have repercussions in the field of physiology of organisms.
Bioelements and Biomolecules
Bioelements are distinguished as primary, secondary, and trace. They combine to form organic
Read MoreLearn Spanish: Numbers, Questions, and Pronouns
Numbers in Spanish
- One – Uno
- Two – Dos
- Three – Tres
- Four – Cuatro
- Five – Cinco
- Six – Seis
- Seven – Siete
- Eight – Ocho
- Nine – Nueve
- Ten – Diez
- Eleven – Once
- Twelve – Doce
- Thirteen – Trece
- Fourteen – Catorce
- Fifteen – Quince
- Sixteen – Dieciséis
- Seventeen – Diecisiete
- Eighteen – Dieciocho
- Nineteen – Diecinueve
- Twenty – Veinte
- Twenty-one – Veintiuno
- Twenty-two – Veintidós
- Twenty-three – Veintitrés
- Twenty-four – Veinticuatro
- Twenty-five – Veinticinco
- Twenty-six – Veintiséis
- Twenty-seven – Veintisiete
- Twenty-eight – Veintiocho
- Twenty-